An on and off problem developed yesterday, a racing engine instead of the normally putt-putt idle. tapping my foot on the pedal would bring the rpms down, then they would quickly go back up. this racing would kick in and out on its own as I was driving or idling. so far today it is operating normally but Ive only bene around the block a few times. any suggestions would be most welcome, and thanks.

Try simple, cheap remedies first.

The mirco-switch that tells the idle control valve that the throttle position is "in the idle position" that is no gas pedal pressure could be out of adjustment. You need to hear (or feel) a definite click when the throttle position returns to rest. If not, loosen its mounting screws and position it until it does click.

Another simple, cheap, possible fix is a loose connection at the idle switch or idle control valve. See if there are any frayed or abraded wires anywhere.

Another possibility is that the idle control valve is sticking. Take it out and clean the inside with carburetor spray.