What causes for a Suzuki Sidekick to idle at 5000 rpms?

if this is the 8valve engine.

the Dashpot vacuum device must not be actived on a running car (after 10seconds)

or the VSV to it is malfunctioning. (this device DP is behind the throttle body)

or lost vacuum to it .

on 16v, the IAC thermal air valve most not be stuck open hot, it must be closed hot.

100% make sure coolant hits 180F (150f is threshold) or the IAC will fail.

and scream it will.

All 8v engines scream for ANY vacuum leaks. Speed density tech.

all 16v scream cold but go lean and stall for vacuum leaks. (unmetered air rules)

look for a vacuum leak on top of the intake towards the front. on mine it was the line connected to the two valves attahed to valve cover.mine is a 1989 so i don't know if yours is in the same place but it's either a vacuum leak or the idle speed control.a