1988 Ford E350 Fuel issue?
I have a 1988 Ford E350 Class C with a Ford 460 EFI motor. The converter was stopped up when I first got it but I removed it and replaced with a pipe so it has been running pretty good since then. It has about 27,000 original miles and I have replaced the in tank fuel pump, fuel filter, added new plugs and spark plug wires, distributor cap and rotor. It has always gotten about 8-10 mpg. On my last trip it seemed to run fine (cruise at about 62) but the gas mileage has dropped to about 5-6. When I got home it runs great from idle to about mid range then it seems to start stumbling if I push the pedal to the floor. It still runs but doesn't seem to make any more power. It seems to be fine until you get on the gas hard. I checked the fuel pressure at the rail and it reads 32 at idle and if I rev it up high it stays steady at about 36 but the motor seems to start stumbling. The pressure doesn't lose any. Does this sound like a bad high pressure pump under the driver side or a bad ignition module? I haven't removed the filter to check it yet but it is fairly new.