why wont it run like it should

[mustang16125]

Thanks for any opinons. i recently bought a 1990 f150 5spd with an efi 5.0HO out of i think it was an 86 crown vic. its using all of the factory harness and computer that came with the truck. I bought the truck off of my friend who rebuilt the engine. He hasnt given me the specs on everything he did to it yet. I belive everything he said he did to it. The truck has high compression pistons, ported heads, a very lopey cam, 1.6 rocker arms (he thinks), double roller timing chain and some other little things. he built the engine a while ago and then never drove it. The truck idles fine and sounds great. Ive owned 2 other 87-91 5.0 f150's and i know this one has more power in lower gears 1st & 2nd , but it falls on its face in 4th and if the road is uphill at all...it will barely push itself in 5th gear. the truck has 3.55 gears i was told. i havent looked for myself yet. I know this is a mustang forum and all. but who better to ask about a 5.0 than you guys? i also know that speed density is very touchy when doing anything major with the engine.....so what do i need to do to get this thing to run right? thanks again.

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[Joel5.0]

Suggest to start ID'ing exactly what the mods consist of. Lopey cam + SD EEC system is not a good match for driveability. LUK