That is what he said. A tight exhaust valve.

 

Well, when valvetrain starts to wear out, it will tighten up. I doubt it the problem would be caused by just one tight valve.

I would advise a compression test.

 

I also have an 06 with a similar problem, but it does not die...only rough idle with running the A/C if the car hasn't been running very long.

 

I've noticed this with my 06 lately. Usually right when I fire it up and have the a/c on(and only if it's pretty hot out). I figured it was just due to heat soak from the car just sitting in the heat and sun. My car hasn't died from it though... the RPMs just dip, and the car shakes a tad.

Car has 41k miles.

 

I've found that a low idle stumble can be fixed by resetting the ecu, and then proceeding with the warm up procedure where you let it come up to temp and the fans cycle on and off twice. It seems to help if the car is not fully warmed up.