slight mis-fire where at is the question

[98gpking]

i got a 1996 Lt1 trans am. its the WS6 if that helps any. there seems to be a misfire i belive. the car sounds like its running ok from the exhaust when im at a stop light and i take my foot off the brake the car shakes pretty hard. theres not a really bda shaking all the time but then again theres 7 other cylinders going too so i wont feel it as if it were a 4 banger. i bought new iridium IX plugs from NKG i can only get in 3 of the 5. the 3 i got out looked pretty new and recent. they didnt look to burnt or anything. the wires werent glues on like some said they wwould be. the wires are on 7mm. do you think maybe the wire is to small and should be a 8.5 or even 9. hers the work it has done see if you can tell maybe one of the aftermakret parts cuases the vibrating

edelbrock long tube headers
3" exhaust
3" offroad downpipe
3" cutout
borla muffler
B&M shift kit
(suposudly) B&M racing chip

[CreepingDeath94]

Whats the mileage on the engine? The LT1s, and all small block chevys really, have had the issue of valve seals leaking and dripping oil into the combustion chamber...especially the notorious cylinder number 8. On that car, it is one of those hard to reach plugs so chances are if its mis firing due to the vlave seal leak, its on a plug you havent changed yet.

If its not a valve seal, and the other plugs are old and you could only change 3 of 8, then unless the 3 you changed were terrible, you would probably still have the misfire. The 7mm plug wires should be adequate enough as to not create a misfire by the way. Another thing you may want to check is the optispark. If it is old or warped due to a leaking water pump you may have issues there.

First thing Id do is finish changing out the spark plugs and wires and see if it clears up any...