Warm start up surging idle/stalling out

[dubya]

hi, im new here but i did take some time to look over the "surging idle checklist" but i was unable to find the same symptom my 87 gt has.
a few months ago i got a motor from a 92 gt, i took the engine, the computer and had a new MAF installed.
when i do a cold start up it will be fine, but if its a warm start up my idle will shoot up to 1500rpm and fall down to nearly stalling out and keep up the process, most of the time it will stall if i dont try and hold the rpm at 1k otherwise it will level itself out to 800 rpm after waiting for a few minutes.

my local shop that works on a lot of foxbodies is hell bent on the fact its a "b-303" cam thats making it do it, but im not sure about that one

any help is appreciated
thanks

 

[jrichker]

Did you dump the codes? What did you get?

What happens when you unplug the IAC/IAB?

 

[Kaseyinupt]

mine did that and i took the idle air motor off the throttle body and cleaned it real good with brake and parts cleaner and it cleared right up. just work the valve manually with a small rod or screwdriver while cleaning it

 

[90mustangGT]

Try the first two suggestions and tell us what you got? Ford IAC's are natorious for getting slow and causing this.