94 2.3L 5-Speed Reg Cab Long Bed

When starting cold engine truck fires right up. When engine is warm, truck will turn over; but, it seems something slows engine while cranking then after a few seconds, cranking speed goes back to normal and truck starts right up. It feels like something is "in the way" and momentarily slows cranking speed. I have replaced starter, starter relay and battery; all with Motorcraft parts. This happens ONLY when engine is at operating temp.
Also, when cranking at WOT, truck will sometimes start; albeit, not immediately. I've done "throttle cable mod" with zip ties and have confirmed throttle plate fully open with pedal to the floor.
If it is a leaking injector, how do I determine if it's just a bad O-ring, or something else?

Any input or advice would be greatly appreciated. Thank you.

 

Leaking injector or leaking FPR(fuel pressure regulator) would cause MPG to drop like a rock, which you don't mention
You would also see exhaust smoke from rich running and CEL(check engine light) would come on

Injector "O" rings keep air out so bad "O" ring would be vacuum leak not fuel leak

Engine cranking speed change is most likely Battery cable issues
A leaking injector causing a "hydrolock" is an abrupt stop to cranking and then it continues cranking, it wouldn't be described as slow cranking, because it would only happen in the one cylinder and only the one time because fuel would be cleared out after that one "hit"

I would clean both battery terminals and also clean the cables ends where they attach to engine and starter motor/relay

1994 2.3l will used a ICM(ignition control module) located on the front of lower intake, these are "known" to get heat sensitive, they run HOT, which is why they are located behind the fan so they get air cooling
When engine is off so is the fan.....................so they can get heat soaked, so when you restart warm engine they may not work at first

Starter motors can suffer the same fate, they can get hot because of their location, so can draw/need more AMPs on a warm restart, vs a cold start, so slower cranking speed at first

 

My Fuel Mileage since January is 22.5MPG average. I think I mis-described my issue as "slow starting." When cranking, the first second or so is normal speed and then cranking speed abruptly slows; almost seems to stop for a half second or so. The truck seems to rock slighty when this abrupt slowing happens, it feels "violent," if that makes any sense lol! Maybe like something is in the way? Then cranking will resume to normal speed and truck will start.
I've have no DTC's, i just did a scan( check engine bulb burned out.) I've never noticed any black smoke to indicate running rich. Truck runs and drives I'd say close to perfect as you could expect of a 94.
In the meantime, I'll clean up the connections and see what happens. Thanks Ron!

 

Also, I've checked FPR and Vacuum line is dry.

 

Maybe try to replace ICM or crank sensor, they are not that expensive. Get an OBD1 scanner too, like $20, it will help you in this case.