I'm having problems with hesitation. I have a F150 Scab 4.6L. I just recently replaced all spark plugs and wires, changed the oil, transmission fluid, and ran some fuel injector cleaner through it as well. Any ideas? It only happens when I get on it hard but not hard enough for it to downshift. If it downshifts it has no problems. I'm sure the engine is getting tired, it has 150,000 mi on it. But it should hesitate like this. Please help me out here.