1997 Geo Prizm Base 4 Cyl 1.60L
What could be causing excessive high revolution per minute when engine is cold & in 2-3 minutes normal?
250, 000 miles. Happened last few months in Missouri in Sept, Oct, Nov and now in Dec. Starts easy. Runs smooth. Good gas mileage.
Several possibilities; vacuum leak, faulty idle air control (IAC) valve. Check on-line for the many parts supply sources, such as; www.autopartswarehouse.com or www.rockauto.com for the replacement parts. For example, the IAC lists for around $176.00 for your vehicle.