i've got a 96 gt with the 4.6 in it. motor is all stock except k&n filter and flows. my problem is this, when i shut my car off it continues to run for about 5 seconds. with that said it doesn't do it all the time. it happens even if the motor is cold and i start it and turn it off after it starts up. when driving it has a miss during exceleration. and that doesn't do this all the time either. any ideas?

 

Sounds to me like its in your ignition.

 

With it missing, has it thrown a code yet? If so, that would be a big clue as to what is wrong.

 

If you're not getting CEL , I'd check your plugs.Make sure you have correct heat range and gap. Over advanced timing,lean fuel mixture, and cooling problems can cause preignition. Good luck.

 

hasn't thrown a code that i know of, but then again i don't think there is a bulb in the check engine light.

 

I used to have run on with my 1971 chevelle. I had a msd 6a ignition. They warned you in their instructions that run on was a problem. Some times I could pull the key out and drive the car until it ran out of gas. I remember most of the problem was caused by the voltage regulator.
It would be a wise thing to check your bulb for the CEL.