I have a 98 Expedition 4*4 5.4L Engine and I am having a problem that no one can seem to solve. When driving the SUV after a few minutes of warm-up the truck starts to hesitate and jerk on acceleration between 40mph-55mph. It gets worse going up hills. Also, I have noticed a slight loss of power. No CEL light has shown up yet either. I have changed the spark plugs, had the fuel injector checked and cleaned, had the PCV valve and the fuel filter changed. replaced coil #4 twice. If anyone has an idea what is causing this problem, please respond?

 

Had same issue on my 85 LTD w/3.8L V-6 @ about 97,000 miles, 92 Aerostar w/3.0L V-6 @ about 83,000 milesand 97 Explorer Sport w/4.0SOHC @ about 90,000 miles. No codes and nobody could fine the problem. Issue was caused by faulty TPS sensor in all 3 cases. TPS sensors had dead spot(s).