2001 Jeep Grand Cherokee Larado V6, rebuilt transmission, 92k miles, 2wd, no other problems that I can remember. Its my 2nd vehicle, so for about the last year, it has hardly seen any road time.

I let my Jeep sit for about a month without starting it. Before that, it idled fine and had no problems. I jumped it and when driving it around I noticed that when I come to a stop or let it idle in neutral, the RPM gauge fluctuates between 400-1100 (1100 is normal). It literally sounds like vroom (up to 1100) then drops down to 400...up, down, up, down, until eventually it dies after a couple mintues. It starts up just fine after it dies (or stalls out) every time.

I just put a 1/2 tank of new gas and drove it about 30 miles to see if that would help any. I didnt, but what I noticed, is that it runs just fine other than when I have to come to a stop. Then the up, down, up; down idle is noticeable.

To combat stalling out at a light, I put it in neutral and keep the RPM at 1000 until I need to go. Any idea what could be the problem? Thank you.