is your check engine light on?

 

I have a 1996 Jeep Grand Cherokee that has the 4.0 straight 6, it has a cracked exhaust manifold so therefor it just likes to go through o2 sensors. Anyway this post reminded me of that, we thought maybe IAC because when we would come to a stop or slow down the rpms would drop and almost die, but once completely stopped it would jump the rpms back up. Our Jeep would actually smoke black from running to rich, ended up being o2 sensor; just a thought hope it helps let us know.

 

I'm betting there is a vacuum leak or the iac is taking a crap.