Engine Idling With A Surge

[Twotirefire5.0]

I've been reading alot of threads about idle issues and surges. But none of them seem to be what's happening to my mustang. It's surging from about 800 to 1200 rpm give or take. I've checked vaccume and pcv issues and iac and tps and all that mess but nothing seems to change. Besides when I replaced the iac it started surging instead of high idle from the old iac. I don't know what the problem is. The car has a b303 cam and gt40 intake and stock injectors.

 

[Twotirefire5.0]

The mustang is a 1993 lx 5.0 by the way.

 

[squeak93]

follow the instructions in the thread exactly. It solves 99% of issues.

Help me create the "Surging Idle Checklist" | Mustang Forums at StangNet

 

[Twotirefire5.0]

I was messing with it last night and I noticed that my battery guage fluctuated with the surge of my idle and the interior lights dimmed and brightened as it surged. Could that be battery or alternator problems And not anything to do with vaccume, iac or pcv related issues?

 

[squeak93]

it could be a million things... hence the checklist above. Work it top to bottom as it states and you will have your culprit.

 

[Twotirefire5.0]

Okay. Thank you for the list of what to do and the fast response.