So I have a 2005 Grand Cherokee with a 4.7L. I have the extended warranty and took it to the shop 2 months ago for this issue plus some others and was told they could not duplicate it. Now the issue has become more pronounced and before I take it in and have to argue to not pay my $100 deductible again I need some help.

I'm hoping you guys with more experience can help me out.

The jeep has a very weird idle about 25-50% of the time. It dips below 500rpm and will rev to 900 rpm all while my foot is on the brake. Sometimes it will even stall out completely. It starts back up fine as if nothing happens, but the process repeats itself. I have noticed while driving around that the feel of the engine is definitely different now. I can't explain it, but its like a very slight sputter.

Any Ideas?