Have you checked the condition of the plugs. They could be fouled. My Z28 I got cheap because of a similar problem. The opti went out, so the old owner replaced it and it still ran like hell. No power, guzzled gas, smoke out the pipes like no other. I pulled the plugs and replaced them and it ran like bat out of hell. Because the opti went bad, fuel wasn't burnt well, so it just built up on the plugs. Check firing order, then check plugs. If it's the plugs are in question.

 

I haven't checked them, but they should clean up after revving it up a bit, shouldn't they? They're NGK Iridium IX plugs. And changing them is a bitch, haha.

 

well plugs is the easiest fix, if they are the problem. i changed 2 while on the phone with my left hand in under 10 minutes. driver side.
i would at minumum pull 1 from each side and see how they look.
hope u figure it out soon

 

If this was my car I would go back to the dealership and ask for my money back and tell them to fix it for no cost. Charging an hour for spark plug wires is total crap. I had someone try and do this to me when I had my 5.0 mustang and getting the o2 changed, they charged me triple the price they said and installed a used sensor. After finding this out I went back and got all of my money back and lots of "Iam sorry"
-Brandon

 

it was crossed wires.. #6 and #8. they are liars.. i'm going to write them a nice letter demanding a refund.. thanks for your help everyone

 

damn, very glad u got it figured out. i wonder what they have to say about that? 750 bucks and they cannot even do a simple job right. i cant stand *shady* mechanics

edit * *

 

I would right them a nice little letter to both the general manager and to the main company. I would not let them get away with this, I would also get the name of everyone you delt with and put them in the letter.
-Brandon

 

You didn't hear any backfiring?

 

after i swapped #6 and #8 back to the correct location or before?

before it was backfiring about once per second at 2000rpm.....

haven't heard any since.. and the engine isn't rocking back and forth like a scared animal anymore... seems to be nice and smooth again..

if you mean after, why do you ask?

 

A "polite" and factual letter is what is required. Be very specific about the dates, and the actual cost and conversations. Be sure to emphasize the fact that they checked the firing order twice, and failed to find the problem both times. Make sure the spelling and grammar are correct - it gives the letter more credibility. Be sure to copy the GM "zone" office on the letter.

There really is no excuse for this type of incompetence.

 

There is no excuse, at all. This is very good advice. A letter that is polite is going to receive much more attention than one full of curse words and threats. Keep this post in mind when you write the letter.