After a routine tune-up, my Grand Cherokee would stall constantly at low idle and the acceleration would quit if I let up on the gas pedal right around 50mph. I had to wait til it dropped below 40mph, then give the gas a good hit. I'd feel a clunk and then a sudden forward burst of speed and it would run normally again until I let up on the gas pedal between 40 and 50. Also, the gas mileage has plummeted from 17-18 to about 10mpg.
The tune-up replaced plugs, wires, distributor cap, rotor button, pcv, thermostat and fuel filter. We replaced the TPS (throttle position sensor) and that didn't help. A friend zip tied the throttle cable, creating a bump stop, and that fixed the stalling idle problems but mileage and acceleration issue still present. I have the 5.2L V8 engine.
Was told it could be timing chain problem? This makes no sense to me. Please help!