Engine Cooling problem
1991 Jeep Cherokee 6 cyl Four Wheel Drive Automatic 80,000 miles
My '91 Jeep Cherokee stalls at redlights and hesitates under acceleration. It will shake violently at a stop. Sometimes when it hesitates it just won't go over 2,000 rpms. I can hold the accelerator all the way to the floor but it won't accelerate until it feels like something " clicks". When it is in motion, it accelerates and drives fine except for the occasional backfire. Sometimes it will not even start. Also, it overheats, running at around 230 instead of the standard 210. This is at idle and highway speeds. The fans do come on. I have replaced the radiator, water pump, hoses, coolant bottle, thermostat, temp cluster gauge, sending unit, and fans. I have also run a compression test and that was fine. My fuel pressure is around 30 at idle, will spike to around 35, then fall to 28 before returning to 30 when I press the accelerator. The engine also seems to start better warm. I have replaced the fuel pressure regulator, IAC, crankshaft position sensor, distributor, spark plugs, wires, fuel filter, and I have run seafoam through the fuel and straight into the throttle body. I have no smoke coming from my tailpipe but it will backfire when I accelerate some times. I am completely lost. I need an experts opinion.
I believe your jeep has both an eletric and one attached to the water pump and has what is called a fan clutch. Check to see if it is loose, it should turn when vehicle is off and it should be somewhat easy to spin. If fan feel wobbly replace is it, if it isn't wobbly and spins fairly easy start vehicle and warm to operating temp, shut vehicle down and spin fan, is spins same as when engine was cold replace it.
As for the lack of power when was last tune up?
The back firing is usually an indication of a timing problem.