So here is what i have been dealing with for about 5 months now. I have a 2008 F150 4.2L v6 and so far I have replaced the fuel pump module, Air filter, fuel filter and added a number of fuel additives to try to cure this on & off again hesitation. I have cleaned the Throttle body and the MAF as well. Some days it runs great and others it hesitates under light load. It had a crappy aftermarket air filter so I thought this did the trick when it ran like a scared rabbit for 3 days. Also the fuel filter had a high content of H2O when I blew it out as it seemed to be plugged. If I start the truck and it warms up for a few minutes then chances are it won't hesitate. If I pump the gas pedal a few times firmly before cranking the engine it won't hesitate or there is a better chance it won't. I hate throwing money around hoping to see if this will fix the problem since I am a bit strapped right now. It's a very slight hesitation so it hasn't left me on the side of the road or smacked my face into the steering wheel with any violent bucking.. Anyone have any suggestions?