Please stop using starting fluid on it. These trucks have glow plugs that can ignite the starting fluid prematurely and could cause major damage or serious injury.
If you absolutely HAVE to use starting fluid, at least disconnect the glow plug relay to disable the glow plugs.
Your problem sounds like an intermittent electrical problem, possibly with the ignition switch (mounted on the steering column just inside the fuse panel access). It could also be either the IDM or PCM relay that isn't pulling in properly.
If your scan tool didn't pick up any codes, it must be a generic tool, most of which aren't capable of pulling codes off a PSD. Like Tom said, if the check engine light was on, you WILL have codes stored.
His suggestion of disconnecting the ICP sensor is a good one to try also. It will cause the CEL to come on when you do that, but the computer will use default values to run the engine.
First truck -- 1929 Model A Ford pickup, restored from ground up. Wish I still had it!
99.5 F250 PSD Supercab LB 4x4, ZF-6 w/SB Con OFE, 3.73LS, Boost & pyro gauges, Swamps S175/146 injectors, DP 80 HP Econo PCM (classic version
), AIS, coolant filter w/"hokum" bracket,
regulated return, heated mirror mod, lighted cupholder, Marinco heater plug-in.
Hard or no-start? Check Here