I bought a 89 jeep cherokee xj 4.0 and have had problems with it since I bought it but now one I just don’t under stand I was driving perfect and all of the sudden it wouldn’t got even if you touched the gas and does some weird idle problem like it doesn’t know where I was to be cuz it goes from 1000 to 1200 and back and forth and since then I have replaced the cps the throttle positioning sensor fuel pump fuel filter new spark plugs again new cap ballets resister fuel pressure regulator air filter checked all my relays and then I was looking at the forums and it said it could me a blocked muffler so I checked those and just for better measures cut it off and still doing the same thing ever once in awhile it will run just fine then go back it what it’s doing I’m just confused at this point thought you guys might have another thought on it

 

You could try cleaning the Idle air control valve. Maybe also clogged injectors?

 

Go to www.cruiser54.com and complete Tips 1,3,4, and 5 FIRST.
Then, readjust your TPS if needed, per Tip 8.