1994 cold starts pulsating rpms

[94 lngbd]

I did a search for all forums & also in this forum & had no results.

When truck is cold it starts up right away ,but during the first 5 minutes the rpms are pulsating if I let it sit to warm up. After this short time it will continue to run perfectly smooth. Some times during those 5 minutes it actually dies.

If I start up & drive away it doesnt seem to effect it at least not that I realize.

I thought I had seen a write up about a sensor that would cause this ,but haven't had any luck with the search feature.

I would like to get this issue fixed.

 

[scotts90ranger]

Could be a dirty IAC, it's mounted to the back side of the throttle body with a 2 wire connector. Clean that with carb cleaner then put it back in. The other possibility is a dirty MAF, or just in need of a tune up, something is happening in the time it's in open loop but works when it's in closed loop fuel control.

 

[WiscoRanger]

mine has done the same for quite some time, but nothing has become of it. ive always kind of thought it may be a vacuum leak where pressure can build, but seeps out on occassion