Idle jumps up randomly when I come to a stop

[Champ10187]

I have a 96 GT with 70,000 miles. I just got it last week. The only mods are an O/R h-pipe with a flowmaster catback and a K & N. The only problem is when i come to a complete stop and the idle drops to 900 or so, it will suddenly just bump up to 1100 or 1200 and come right back down again. It will it do it every 15 seconds or so when i am at a stop. ANy ideas what this could be??

Also, my ABS light is on, not sure what the problem is but is there any way to get rid of the light without taking the bulb out? thanks

 

[ImportEater98]

Is the car stick or automatic? When it does this, is the A/C or front defrost on? Is the air intake tight on the throttle body? As for the ABS, check the fuse first...thats the cheapest....is the light blinking or solid?

 

[daver01]

might try cleaning/replacing iac valve. my 01 did this when i got it, & it has been fine ever since.

 

[Champ10187]

Is the car stick or automatic? When it does this, is the A/C or front defrost on? Is the air intake tight on the throttle body? As for the ABS, check the fuse first...thats the cheapest....is the light blinking or solid?

i just realized that it only does it whne the A/C or heat is on....what is the reasoning behind that? I checked the fuse and its good, the light is solid..

 

[daver01]

if it only does it when the compressor is running, it is normal. mine does as well. my guess is the extra load on the engine causes it to 'hunt' for the right idle.