idling problem

[Crazy4408pac]

98 Monte. Over the past month, when the Monte is started, it idles around 1500 rpm. Letting it warm up, doesn't help. Blipping the throttle, doesn't either. Which causes the rig to run around 45-50 mph with my foot off the gas. It doesn't happen all the time. Maybe a dozen times.

Any ides?

Thanks

[Schurkey]

Connect scan tool, find codes. Also find the commanded idle speed.

 

First Guess: Defective Idle Air Control.

[AL]

Could also be a vacuum leak