I have a 98 e150 with a 4.2 V6 and it is sputtering under acceleration, kind of like its getting choked out or running out of gas and usually backfires during this. I have replaced the plugs, wires and fuel filter within the past 4 months. When I do a full throttle acceleration the problem is not as bad but still exists. I replaced the coil pack when this started with no improvement what so ever. Any help would be greatly appreciated.
If your check engine light is on have the computer codes checked at autozone or advance auto parts or somewhere like that (hey check them for FREE). Post the codes here so that we can assist you in diagnosing the problem.
Also, use (rent) a fuel pressure gauge to check the pressure at idle, acceleration and at full throttle. Compare them to specifications. Again, please post the results here for further assistance.