As title says my RPMs fluctuate ever so slightly when I let off the gas.
It doesnt do it at a sitting idle, only when I'm driving and I let off the gas

side note: my check engine light comes on sometimes and may stay on for a week or more then it goes out for a while again and usually comes back on in another week or so


any ideas what might cause this?


thanks for your help and experience

 

Well, your engine light means it's trying to tell you something so that would be a good place to start...

Slightly fluctuating rpms when you let of the gas is pretty normal. It can have a few causes. Unless you mean surging up and down.
Can always clean the TB and IAC if it bothers you and you'd like to go down the path of trying to sort it..

But get the codes first, before anything else. The check engine light is there for a reason.

 

How are you going with this? Got the code(s) read yet?