89 xj idle problems

i have an 89 xj that i cant seem to get to run correctly. when i start it up it tries to die on me even if it has already been warmed up. also when driving the rpms kick way up and just stay there. the rpms will also kick down really hard and then kick back up. i have it looked at but no one has been able to fix it. any ideas?

First, tune up. Plugs, cap, rotor, air filter, and clean the intake and throttle body. Have all those been done recently?

How many miles on your Jeep, and what transmission do you have?