2006 E350 5.4L 2V - 95,000 miles

I know this is an E350 on an F150 website, but hopefully you guys can help. I have seen many other posts on here but hope my information might help direct me into the right direction.

A week ago I was driving down the freeway & the check engine light came on & I could tell it was misfiring. The check engine light would blink on & off. After a mile or so it went off & the power of the engine was restored. On my way home, this sort of event happened a few more times. Eventually by the time I reached my off ramp, it stayed off all the way home on the surface streets. The codes I retrieved was P0003 random misfire on cylinder 3,4,5,7. About 8,000-10,000 miles ago I replaced the spark plugs with motorcraft plugs, So, this time I replaced the coils using motorcraft coils. For the last 4 days it’s been running great. Then this morning it happened again when I was cruising between 70-75 mph. If I took my foot off the throttle & went down to approximately 60-65 mph the check engine went off & the misfire was cleared. I went back up to 70-75 mph again & the misfire returned with check engine light in tow. I then took it back down to 60-65 mph & drove the rest of the way to work (about 15 miles) with no incidents. I checked the codes & they were the exact codes I had a week ago (and yes, I cleared the old codes out). At this point I’m kind of confused where to try next. I have read countless posts online & people going this direction or that direction. I don’t know if it’s coincidental but a week ago when this all happened, I just filled up my gas tank. I just trying to cover all bases.

 

replace the fuel filter and do a fuel pressure test.

 

Looks like the E-vans had a FPDM but I have no idea where it's located. On the F150 it's subject to corrosion. If it has a FPDM there's no fuel pressure test port and you have to use a OBD2 scanner to read out the fuel pressure PID.