What causes an abnormally high idle in 1988 Jeep Cherokee?

Answer 1

It could be the IAC module that sits next to the throttle body. It controls your idle and is non-adjustable.Try cleaning toyr throttle body system first, if tht doesn't work it will need to be replaced. Good luck, Mike

Answer 2

check coolant level clean throttle pate if you have ac the condenser will cause an idle change about once every 20 seconds

Answer 3

It's almost always a vacuum leak, but it can also be a sticking throttle assembly.