Oxygenated gasoline
 

I don't know about other states, but in Calif. the gasoline is oxygenated from, I believe, November, through February. I've been told that oxygenated gasoline can cause some "vapor lock" type problems if the weather gets too warm.

My car has been idling roughly off and on for a while. Today I put some gasoline in the car, which I believe is now probably non-oxygenated, and so far the idle is very smooth. Could the gasoline have been causing or contributing to the rough idle?

I've found some stations around LA, have just a crappier gas.

I try to use Chevron mostly.

My car had some weird problems, and I filled up at a station and they went away.

Filled up at another and they came back.

I would run some injector cleaner through your engine, and see if that helps out.

But I like the oxygenated theory you have, sounds like it could possibly be an answer. I am interested in finding this out too.

Alon