My '92 (in sig) Starts, idles, runs and drives perfect. No problems at all, except when I lightly press throttle the idle dips, sometimes almost to a stall point but never does. And it doesn't always do it. Could it be bad TPS, IAC or just dirty IAC and throttle body? See video attached. Thanks,
Blaine

The truck is idling fine its me lightly pressing the throttle to show you what it does, it always bounces up and idles great.

http://www.youtube.com/watch?v=MGzvdd8afaU" target="_blank">http://www.youtube.com/watch?v=MGzvdd8afaU

 

Could be a sensor problem(pull codes to find out) but it could also be a vacuum leak. I had an '89 that did the same thing and turned out the vacuum can on the passenger inner fender was rusted out on the bottom.

 

I recently checked for codes and didn't have any . also it doesn't always do it and sometime when in gear when going after a signal, itll drop a sec then go. kinda annoying . Vac leak could be possible because every once in a while at idle itll surge about 50 rpms or so. not very noticeable but to me a fly landing in the bed is noticeable lol