All, I could really use your expertise. I have a 96 Cherokee 4.0L that has an intermittent rough idle condition at startup but does not trigger a CEL. I have had it in several shops over the last 2 yrs and sometimes they can make it a little better for a little while but it never totally goes away. I'll do my best to describe it here.

Symptoms are:
1) Upon starting you have to pump the gas to get it started and need to keep it above idle or it will shut off.
2) Also when this is occurring the shifting from 1st to 2nd is delayed. I have to let off the accelerator for it to shift to 2nd.
2) After a few minutes it will idle smooth and shifting appears normal

It only happens on the vehicle when the engine has had time to cool down such as over night or while sitting at work. It does it during the summer as well as the winter. It doesn't do it all the time. For instance, the past two days it occurred when I started it up in the morning but not in the afternoon. Last week it would also do it in the afternoon. Had it in the shop over the holiday and sometimes it would go a day or two before it would occur. The IAC has been replaced about 3 months ago. The fuel system was cleaned several times over the last year. When it was in the last time the tech sprayed some cleaner in the intake and noticed a black and green junk coming out of the exhaust. They could not determine the cause but thought the fuel system may be dirty. He recommended running a few tanks of 93 octane through it with the fuel treatment added to the tank. We will be doing that over the next couple of weeks. So far we have ran one bottle of cleaner through but haven't had to fill it up yet. Will need to fill up later this week.

Do you think this is the correct approach? Anything else we can try or check?

Thanks...