98 Rodeo idle problems

Lately the engine on my 98 Rodeo can’t seem to decide which extreme it wants to be in. When I start it up it either dies without my keeping the engine reved, or the engine revs and stays revving. After driving for a few minutes it settles back into normal.

I would clean the idle air control valve (IAC). Its right at the throttle body somewhere.

The check engine light isn’t on is it?

I’d add checking the Coolant Temp Sensor in addition to the IAC valve. A service manual should have what the resistance or voltage specs are for a given temperature range.