My 89 4.0 A/T 4wd cherokee gets to 20mph then bogs down

Take it to a garage and check the OBD codes.

ck your fuel filter ........ in extreme cases the fuel rail regulator or fuel pump will become damaged and not allow proper fuel pressure to occur ( limp mode) computer stores a fault code 4 this as well

Don't waste money on sensors, If it is electrical the check engine light will be on, In which case use a scanner to determine the problem, If no code it is most likely fuel related. Also check vacuum lines.

you either have a plugged fuel filter, a plugged converter or a bad mass air flow sensor

had the same thing happen to me! and it turnned out to be a blocked catalic converter

ENGINE BOGGING DOWN ON ACCELERATION.COULD BE FAULTY TPS SENSOR.STOPPED UP FUEL FILTER AND STOPPED UP FUEL INJECTORS.

ok if the timing chain was bad it would not run. bogging down is from increased resistance from something. since you have overheating i would guess the water pump broke when you heard the sound. ther is a belt around it and that would cause this. since it idles fine i would wait till it is cold and open the radiator then run the engine and see if you see water moving in the radiator. if nothing after 10 min then i would suspect the water pump. watch that you don't overheat the engine doing this. that would cause other problems that could be more expensive to fix good luck

It could be the throttle position sensor, yes. What does it do once you reach 20mph? If it just kind of bogs out, i would check for a plugged exhaust. It never hurts to pull out a spark plug or two and see how they look.

Make sure that the timing is correct and that the spark from the coil is healthy. Problem can also be with the overdrive in the converter. If it's stuck on it can do that too.

go slow in the car about 15 to 20mph then put the car in fourth gear and accelerate if the car bogs down then the clutch is good if the car revs up then the clutch is slipping.