It idles fine at 700rpms when initially cranked, but after driving it for a few minutes, it goes up and stays around 2000rpms, when taken out of gear. Why won't it go back to the initial normal rpms?

The power steering pressure switch may be bad . This switch idles up the engine when the steering wheel is turned left or right to keep it from stalling .

Its no YJ 1990 wrangle. its pre 1986

a real shame for you not posting year,jeep'
1953 to 83? 30 year of CJ5
is it a CJ5 in USA? with 6 different engines
and carbs, i'ts not fuel injected. like poster answered. hit helpful for me guessing CARB.

"OP has CJ5" no year stated.
what transmission auto or stick???????
QOD,so what is it.
134 cu in (2.2 L) Willys Hurricane I4
225 cu in (3.7 L) Dauntless V6
151 cu in (2.5 L) Iron Duke I4
232 cu in (3.8 L) AMC I6
258 cu in (4.2 L) AMC I6
304 cu in (5.0 L) AMC V8
192 cu in (3.1 L) Perkins 4.192 I4 diesel
australia
1965 Falcon engine/clutch components

and Brazil wow. wild stuff there. ill skip that.


now my answers are On topic idle racing.....

1:choke sticking on hot, stuck on fast idle cam
2:carb running rich with vacuum leaks
3: dash pot valves on CARB sticking.
4:gun under throttle plate

left air cleaner
if choke is closed, open it by hand
done 1000 times...
idle drop fast BINGO.

Clean throttle body and idle circuit, link below, press the helpful button
Idle Air Control Motor Cleaning For Wrangler