I just recently had an issue with my 2002 f150 4.6l. It was acting like a spark plug misfire, which is a simple fix, but after getting a diagnostic done on it the read out said it was my CPS ( crank position sensor ) and after spending $20 or so on the part and doing it myself it still was running rough, so I thought maybe it is my plugs. So I bought and replaced those, number 8 is not fun to replace by the way. Again it was running rough, I was almost about to give in and take it in, then I remembered I just put in around 10 or so gallons of gas and I tried one more quick fix, rubbing alcohol in the gas tank and low and behold I had water in my tank from a contaminated gas pump. So my point is that if you have problems that feels like a misfire or rough idling after refueling then try some rubbing alcohol and save yourself money and a weekend.