Sonoma high idle while driving

Okay now I’m stumped. The compressor is disconnected. Now the engine wants to idle at 2000rpm while in drive or park. Sometimes when not using the heater(off position) the engine runs as it should. Most of the time it idles way to high. Even while driving. Makes coming to a stop on snow covered roads interesting. Almost took out a neighbors garage door. The check engine light is not coming on. So I assume there are no codes to check. We are experiencing a very cold icy winter here in Ohio. Driving is an experience without the truck idling too high on slick roads.
Any ideas?:uhoh:
2000 GMC Noma

While it is idling high- pop hood- listen for vacuum leak- either a hose unhooked, or an intake plenum gasket leak- also it could be a stuck open IAC (Idle Air Control) pintel- What yr truck and what engine?

2000 Sonoma
4.3 engine