My EFI 300-6 in my 87 F150 died at 65mph. It had been running just fine, but then failed to start one day, and had no spark. I took it to a shop where they put on a junkyard ECM and new distributor and ign box. That's when it started running crappy(like maybe starving for fuel ??). I replaced a clogged fuel filter a day AFTER they worked on it, ran it for a month(crappy), then it died at 65mph. It cranks, has spark, fuel pump runs, but not sure of it's pressure yet. It "pops" in the exhaust after cranking for awhile, but will not start. Any ideas - anyone ?

 

I'd take it back to the shop & complain. They obviously didn't fix it the first time, and you've already paid, so they should either fix it, or refund your money & give you back your original parts.

If you want to fix it yourself, get the oldest edition of the Haynes manual you can find. Read this caption:



You'll also need a digital multimeter (DMM - $10-50), a fuel pressure gauge, vacuum gauge, compression gauge, & tools.

 

steve83 would have been right if you had taken the truck back 3 weeks ago... im 98% sure they wont refund anything but will probly help you out, really depends on how small the shop is and your relationship witht the empolyees/owners but good luck