idle

ok so for some reason my idle went from normal(750ish) to a little low(650ish) and is kind of rough now, it still runs fine, its just kind of annoying and I'm not sure what caused it cause it was fine for awhile... any ideas? maybe its the timing?

Lets see...

1. Possible Cas moved (timing)
2. Bad spark plug
3. Clogged air filter?
4. Thermowax/idle stop problem
5. Initial idle setting problem
6. ECU problem..
7. Waterthermosensor problem...

Guess what I am getting at is... Could be alot of things.

Did you scan for codes?

I checked the air filter and it seems fine, but no I haven't checked codes... could it possibly be the gas? it was tuned with 91 octane and last time I filled up I'm not sure if I put in 91 or not, I think I may have put in 87 out of habbit, also it was a tiny place I'd never heard of so I doubt it was very good gas to begin with...

I put in half a tank of 91 today though so hopefully it gets better and that will be the end of it lol

Now don't quote me on this but I don't think 87 octane would cause it to idle rough just cause a slight bit of spark knock under high boost.
I would check the plugs first and go from that.