1990 100 I-5, automatic. As engine warms up the idle lopes between 500-1.5k (close to stalling). Gave a tuneup (didn't help). Any suggestions?

Check hoses for air leak, ISV, then throttle switch.

Good Luck

Kevin

The ISV went bad on my car causing high idle. I never got close to stalling though. You may have more than one problem.
1) Check the throttle switch
2) Clean the ISV with throttle body cleaner.