I have an 06 commander 5.7. When I drive does not matter what speed. Can be driving 20 mph or 80 mph. I reach my desired cruising speed and try to just maintain that speed. I notice that something engages and puts extra load on the motor, I press slightly on the gas pedal and what ever it is disengages and feels like the jeep goes back to normal. As long as I keep a small load on the motor. Any ideas?