1992 f150 7.3L hard start problems

I have replaced all glow plugs and IPC (internal pressure control sensor) , the glow plug relay and also checked fuses for power. Truck will start but it takes several cranks to do so/very hard start. I also checked for fuel blockages. It started okay one day and then was not okay the next day. I worked on this truck since the warranty ran out so I know it pretty good. My 7.3 L 1992 (high mileage )truck does not have a CPS (cam position sensor) according to several resources and Ford so that is not an issue. Please help, I don't know what else to check without driving it in to hook it up to a computer at Ford. I am a mechanic but can't figure this one out.

F150?

I'm a Powerstroke guy, but I have worked on a few of the older idi engines also.
You don't have a cps, that is on a Powerstroke. Your engine has very little electronics on it. A computer scan won't do you any good. The early Powerstrokes had very little scan tool use too. I do know diesels though. Sounds like you have an air leak. If you have an air leak that lets the suction off and allows the fuel to drain back to the tank. It is hard starting because of the lack of fuel. I remember that leaking return lines were a problem on those things. They would let air into the system and let the fuel drain back. Look on the supply side too. If there is any doubt replace. Just because you don't see a fuel leak, does not mean there isn't an air leak....

try cleaning your throttle body if that is what you have on your engine if fuel injected your injectors could be dirty as hell

Its a bit frustrating with the older 7.3 Idi's and I had the same problem with mine! As mentioned the fuel return lines are a huge part of hard starting with those, Then came the wiring to the glow plugs(check connections and overall condition of harness). You want a snug connection to glow plug tip. I've also noticed that where the harness that connects to a main wiring harness wires had melted from over cranking the motor(check for that). Once I had that all figured out then came the cold weather, I plugged mine in at 45 degree's everyday for an easy start. Most of all that motor is picky about oil changes, every 5000 miles I did mine. I relied on that truck daily for my Business and took good care of it and it took care of me. Good luck