Help!! please

[Fasano44]

I have a 1997 gtp, a lot of modifications including ported upper and lower intake, 3'4 pulley on s/c, TOG headers with 3" zzp exhaust. Autolite 103 plugs gaps accordingly, Northstar throttle body with adapter, msd coil packs but im having a problem with the idle going all over the place, at times itl stay steady around 800 but other times it gets stuck around 1500 and doesnt come down until i put it into gear, has anyone had this sort of problem? any information is appreciated thank you!

 

[Scottydoggs]

sounds like a vac leak. spray the vac lines with carb cleaner listen for the idle to jump.

and 103 plugs are to cold, 104's gaped at 0.50 would be better.

 

[SgtMarshal]

One time I installed a set of new 103's and forgot to gap them, they had the factory gap of .035. It didn't mess the idle up, but the car ran lean for the minute it took me to remember I hadn't gapped the plugs

 

[mguzzo]

104's gaped at 0.50 would be better.

and gapping to 0.050" would be better still ;-)