AUTOWORKS AUTO CTR

The engine of my '98 Camaro started making a bad knocking sound Monday, 8-12-13.  Being that I'm not a car expert, I drove it down from Fort Worth (where I work) to Cleburne, where my parents live to let my Dad listen to it.  When he listened to it, he thought it sounded bad, but wanted to have a mechanic listen as well just to be sure how bad it was and to diagnose it the problem.  After checking around with other mechanics, finding out that they couldn't get to my car any time soon, he got in touch with Autoworks on Wednesday, 8-14-13.  Keith (the owner) said that he would drive to my parents house at around 3 PM the next day (Thursday, 8-16-13) to listen to the car and diagnose the problem.  After calling him at around 5 PM as he hadn't showed up yet, he provided excuses, but said he would be there at 10:30 AM the next morning.  I was off work that Friday, so I spent the night at my parents so I would be around to hear the diagnosis directly.  Keith didn't show up that morning, but finally showed up that afternoon and concluded a new engine would be needed.  I asked if we could bring the car in to his shop right then, and he said yes.
  Prior to this, Keith said the labor to replace the engine, should it be necessary, was about $600 and that the labor to put in a rebuilt engine for a '98 Camaro would be $800.  Considering I wasn't expecting to have to replace an engine and didn't have the funds readily available, $1,400 at least sounded fairly reasonable. 
  When we brought the car in, the labor cost shot up to $800 and the $800 for a rebuilt engine would now be a " used" engine.  I'm not sure how the labor price shot up 33% out of thin air, especially considering he was driving a '98 Camaro himself.  I would figure a mechanic who drives the same car would know how my vehicle is constructed.  I might understand if he never worked on Camaros, but I doubt he "forgot" anything.  
  Keith explained he could get me a rebuilt engine for an extra $700 (totaling $1,500 for a rebuilt engine, before labor).  A rebuilt engine would've been much better than a used engine, especially since he couldn't tell me how many miles the used engine had on it.  He also said he could have it replaced in a week because would take him two days to remove the old engine and two days to re-install.  
  My Dad and I checked around and couldn't find any engine cheaper, or any mechanic shops that would get to it faster than a week, so we decided to give this guy a chance.  
  If you're keeping score, the original price was $1,400 to put in a rebuilt engine, but the final price was ~$1700.00 to put in a used engine.  Higher price and lower quality, but it would only be a week, right?
  On top of that, I asked if I could place the charge on my credit card (due to the aforementioned not having funds just sitting around for an engine replacement, and I could at least pay it out).  Keith said he had the Intuit hardware (allowing businesses to swipe a credit card over a smart phone), but never set up an account.  Seriously, here in the 21st century, what business is NOT set up with credit card capability???
  To condense this part of the story down, from the day I dropped off my car to the day it was picked up (supposedly fixed), it was 24 days later...not exactly a week and not exactly fixed.
  The car was picked it on Monday,9-9-13, and "Service Engine Soon" light already came on while taking it home.  As it turned out, the problem was the car would stutter when accelerating.  This is a problem, more especially so when trying to get on a highway, needing to speed up with the traffic, which I frequently do.
  The biggest problem with Autoworks is Keith isn't around to actually work on the car.  In a regular week, you'd expect most car shops to at least be open to 8AM to 5PM. Heck, many mechanic shops stay open to 6PM knowing most people can't leave work until 5PM.  This guy would regularly not come in until 8:30 or 9AM, would be out for lengthy periods at lunch time (11:30 AM to 1:30PM), and closed up shop at 3PM.  So, in a normal 40-hour work week, this guy was around only 25 to 30 hours.  How much more work he could get done if he were around another 10 or 15 hours a week actually working on cars?
  I was fortunate to have my Dad help me out and he would go by periodically to check on the car during the day...if nothing else than to remind Keith how important it was to get the car back in a prompt manner.  The funny thing is, when I brought my car in, Autoworks didn't have any other cars on the lot to work.  However, it was apparent Keith started receiving subsequent jobs and was skipping the work on my car.  My Dad eventually had to give him some stiff words but was basically saying "You're not working on the Camaro".  Keith tried the excuse that he had other cars he needed to get to and those cars were important.  He was reminded that my car was important as well (again) and that it was there first.
  As stated earlier, the Camaro was picked up on 9-9-13 and the "Service Engine Soon" light came on almost immediately.  Judging from previous Camaro experience, my Dad and I thought the EGR (Emission Gasoline Recovery) valve was the problem.  Replacing this valve had solved a previous, and similar, stutter.  We went ahead and took it back to Autoworks to see what Keith would say.  This was on 9-13-13, another off-Friday for me.
  Keith plugged his little machine into the Camaro's computer, and looked around the engine like he didn't know what the issue was.  He thought it might be the Coil Pack for the #3 cylinder.  So we brought him a Coil Pack so he could replace it.  That didn't fix the issue.  While we were there, I mentioned that maybe replacing the EGR valve would cure the stuttering.  Keith didn't much act like he even heard the suggestion, and if he didn't, he didn't really much confirm or deny that replacing an EGR valve would do anything.  He suggested that we bring it back in the next week and he'd look at it.  I decided to order an EGR valve, and replace it myself because the valve sits on top of the engine and is easily replaced - only two bolts and easily accessible.
  I got the new EGR valve a week later on Friday, 9-20-13 and replaced it the next day, 9-21-13.  At first, that seemed to solve the issue, but it wasn't long before the stuttering returned.  On top of that, a new rattling could be felt that was coming directly below the console.  It seem that perhaps a mount or bracket might be loose (or broke) and could be causing the drive train to be rubbing the floor of the car.
  We brought the car back a second time on Friday, 9-27-13.  For those of you counting, that's 6 weeks after I dropped it off to Autoworks the first time.  We told Keith about how the stuttering was still going on and now there's a rattling/rubbing sound under the console that was never there before.  He replied that he had a full day ahead of him and suggested that we bring it back the next Monday.  I honestly didn't expect him to work on it that day, but when he said that I asked him if he could simply put it up on his lift machine so we take a quick look under the car.  (Side note:  for those who don't understand, we wanted to inspect the underside of the car to look for anything obviously wrong.  Camaros sit pretty low to the ground, and you can't simply&