ok im sorry to start a new post, but i want to be more specific to my situation...
i have a 89 f250 with a 351, engine was locked, took the engine out of my 90 f250, also 351 ( 90 was retired due to rust ) dropped the 90 engine in to the 89, wired 90 engine harness to 89 'fender harness', ran "good" except the point i had extreme ping/detonation ( not sure which term is correct ) it sounded like a deisel, immediately shut down... tried to swap the "fender harness", and it didnt line up with the harness's running back the frame rail, no fuel pumps

so i decided to swap the engine harness to the 89 engine harness and swapped the "fender harness" back to the original harness (89) of course to do the engine harness you have to pull the upper intake, did all that put back together... fired up but it runs extemely harsh

it will hold a idle fairly good, but if you tromp on the gas it just cuts out...
if you work the throttle slowly it will rev but misfires....

checked for vacuum leaks by the propane method, did not find any leaks..
timing would not be off that i can figure, the dizzy has never been touched....

have not checked to see if the plugs got burnt from the few moments of ping/hesitation.... plan on checking them tommorow and re-routing the plug wires...

sorry for the 3 mile post, just wanted all info to be included

 

I was gonna say you want to use the '89 wiring and nothing else. Check that the injectors are wired correctly, the connectors should be numbered, and also that the spark plugs are wired for the correct firing order. It should be 13726548 but try the other one if you can't find anything else wrong.. who knows maybe the motor got an old 5.0 cam at some point.

 

i thought the injectors would just fall in line the way the harness wrapped, i will definately look at it as a "after i check the plugs and hope its a easy fix" fails on me lol, and the firing order it ran fine on the 13726548 before, tried to swap them and it didnt even fire up ( might have if i woulda got into the gas, but i did it standing outside of the truck ) is the tab/tad sensors different from 89 to 90?? maybe ford decided to swap the tab/tad plugs to be smarta$$es?? just throwing out ideas, any conformation is greatly appreciated

 

They will but it's still possible to miswire them if you're not paying close attention... have done this myself.

No.. and actually the engine will fire and run the way it should(until it begins to warm up) with most of the sensors and actuators disconnected, the only thing it really needs to see at startup are the TPS, IAC, and the pulsetrain from distributor. It can't tell if the injectors or plugs are wired correctly or if the fuel pressure is within spec so you'll have to manually confirm these things.

 

ok so update... i pulled the plugs and wires, replaced wires with brand new (gotta love warranties lol) and replaced the plugs (which by the way were autolite platinums, ripped them out, they were all covered with a light coating of black soot) put in motorcraft copper cores. the idle smoothed out alot, but i still have issues with when i revv the engine slowly it will climb RPMs but will misfire, seems the worst at about 2000 rpms... if i just ju,p on the gas it will start to cut out like you had it revved and just turned the key off while holding the gas in (kinda like a mini engine brake sound)... while idleing i unplugged the iac and the idle dropped a little, not much, plugged it back in then unplugged the tps and didnt get a single change, what "should" the tps do when you unplug it if it is good??

 

also for quick reference i looked at the 90 engine harness at the injector connectors, and as far as numbered all i seen was on the side opposite the arch cutout on them, and they varied like 55, 56, 8, 5, 23, 32 etc... its random numbers ( atleast random to me )

 

ok update as of today, i checked fuel pressure im sitting at 35 idling and 45 with the FPR vacuum unplugged, so right in spec... also changed the coolant temp sensor, no change, then a new TPS, it doesnt buck as horrible at 2000 rpms WHEN i just plugged in the new TPS without it being bolted to the throttle body housing and did not mess with the sensor like it would be adjusted if it was installed.... im slowly running out of ideas other than the injectors wired improperly, or if somehow it set a different timing through the spout than what the 90 harness was setting it at (is that even possible) or can the pick-up coil die that quick and just give a weak spark ( strong enough to start and run, but weak enough to misfire???)

 

is there any 'real' difference from 89 injectors and 90 injectors, i know i looked them up and they are different part numbers, but it doesnt seem that that should matter as it did not misfire and hesitate when the 90 injectors were run on the 90 engine harness but 89 computer... is there a way to technically identify which injector wiring goes to which injector, not just going by where they fall when you put the harness on is where they go ( it wouldnt be so bad if the plastic rails that attached it t the valve covers was still there, they kept it all in line)

 

You say unplugging the TPS made no difference.. that's not good and could be your problem. Have you pulled the codes at any time since doing the swap? I suggest testing the TPS with a multimeter on the resistance scale(ohms) looking for a smooth increase/decrease in values with no dead spots, if you find any change it.