About 1 Month ago I had the spark plugs changed at pepboys, Brought the car home it was running fine , Next morning i start my car up and it's idle was horrible and would hesitate when i stepped on it,so i take it back to pepboys they said that when i left with the car it was in great condition,They did not warranty my car because I had nitrous. So I take the car to a real shop and have them do a complete tune-up Ngk spark plugs,Msd wires,Msd blaster coil. so I get my car the next day and the mechanic said that I had 3 different brands of spark plugs -Ngk,Bosch and Delco. So of course i was pissed. Anyways I start my car the next morning and again it had a slight hesitation when i step on it from a stop.The idle was better though. So mean while my Hooker long tube headers came in and i installed them last week at a shop and while they installed them they also changed the plugs again because they said that 1 of the plugs had a crack> So the next day I get my car back and my car ran great,So when i thought the hesitation was completely gone it came back and not only that my car was backfiring and had a horrible stumble at any speed like if i stepped on it from 65 it would stumble then it would eventually go but very slowly. So i take it back to the shop where i had the headers installed they ran it through the computer and got a Random Cylinder misfire and i ask if they would work on my car and they said that they only specialized in ls1cars,So i am taking the car to another shop tuesday and hopefully they can fix the problem. So have any of you experienced anything like this? Could it be that my Msd blaster coil went bad.
What do you guys think?

 

I would look further into the plug wires. The difference bad wires being replaced with now OEM ones on my car was amazing!

 

i would have to agree, i had a bad misfire in cylinder 3 & 4 where the spark plug wires are pulled tight and over time , even with ceramic coated headers i ended up burning them, replace them and the car has been running great.
zoso

 

Ok guys today I went to the shop and they found the misfires in the 5th and 7th cylinder and you guys were right a plug wire was bad along with one bad spark plug. So thank you guys for your input.