My 89 V6 (auto) is surging. It's running high revs while in gear (intermittently) and when I switch to neutral they go up past 2000 rpm. I have to apply heavy breaks to keep from rolling in gear.

I can't associate this with hot or cold temps -- sometimes it goes away when the car has been turned off -- sometimes it stays. Sometimes it comes on suddenly and stays, or it never happens at all.

Is it a sensor (I've a vague recollection about an o2 sensor).

I am due for an oil change -- anything I should look at myself or direct my mechanic to look into?

Many thanks

Rob