I have a 1996 Cherokee with the 4.0 and aw4 also it has 180k miles on it. Of recent it has started lossing power when driving at a constant speed, usually in the top gears and rpms between 1500 and 2200. Sometimes very slight and other times big losses of power. It seems to only do it though when the gas tank is full. I have no idea what it is and would like to have this fixed as I have a few trips planned with this vehicle

 

No check engine light?

 

No

 

try running with the gas cap loose and see if you get any changes. if the vent hose for the fuel tank is plugged up its possible that the engine is starving for fuel when a vacuum is being developed in the fuel tank. I have strong doubts that this is your problem, usually this is reserved for vehicles that don't have an actual electric pump in the tank. but i suppose its possible since its only happening when the tank is full.

You may want to rent a fuel pressure gauge and check the numbers as you drive could be a fuel pump checking out.or plugged fuel filter, could be bad ignition components. could be a bad TPS could be a number of things. You should scan it and see if any faults are stored in the history that are not yet triggering the light.. if you dont have a scanner or code reader you should buy a $30 one because you are going to need it if you intend on working on your own jeep.

 

i am going to try the gas cap thing. When this started is about when I bought a new gas cap