I have an 08Fx4 that developed a stalling problem a couple weeks ago. Wife filled it with gas and instantly started running bad. Idles fine but really jerks and stutters under any kind of load. Changed the fuel filter and bought a FPDM but haven't had a chance to try it. After I changed the filter, I drove it 4-5 miles and it ran perfect. I thought I had it fixed but Wednesday evening I jumped in it and took off for town, 3-4 miles down the road it about threw me through the windshield. I'm going to put a guage on the rail this weekend. I don't really think it's a COP or plug, it's more than a typical miss.. When it stutters, it feels like you put it in park. It really bucks. Anybody ran into something like this? Any other suggestions? It has not thrown a code yet either. As a side note, wife filled her van at the same station 10 minutes after the truck and it ran fine so I don't think the gas is bad either

 

Sounds like you need to drain the tank, change out the filter again and if that doesn't cure it, then I would look at testing the injectors...likely clogged

 

There is no port on the rail for checking the fuel pressure. It can only be read out with an OBD2 scanner.

 

Put it on the computer this morning and my fuel pressure was all over the place. From 74 lbs down to 13lbs. When the pressure peaked, you could hear the pump squeak in the tank and the pressure went down to 13.I assume it was the regulator releasing the pressure. I changed the FPDM and problem went away. It was corroded through on the back side but you couldn't see the circuit board.