1987 Ford F-150 Missing and stalling when warm

Hi, Thanks for being here, My truck has some wierd problems. It sometimes misses, I mean like someone turned the key off, the tach goes dead, sometimes it seems to catch and take off again, other times it stalls and dies completely. Ater a few minutes it usually starts again only to have it die again further down the road. Another strange thing it does sometimes is when you step on the dimmer switch for the headlight there is a momentary miss. OBDII shows no codes. I have replaced the ignition module, the ecm, both fuel pumps and the relay, new cap, new wires. All that is left is the distributor pickup and the ecm relay. This is an intermitant problem but appears to get worse when the truck is warmed up. Any ideas? Bob Anthony

updated 1/15/10
I am planning to get the truck inside this week as there is a lot of snow on the ground around here. I will go over the grounds with a fine tooth comb. Do you know of any diagrams that have the ground locations on them. I have a Haynes manual and it has wiring diagrams but there is no mention of where they are. I noticed today when the engine died after opening the hood that the wiring harness that has the plug that connects the ignition module has been soldered together as if the plug was replaced or something. I will check that out too. Another thing I noticed today was that after cranking the motor with the transmission in neutral trying to restart it after it died that it did not start until I put the tranny in first gear! Any ideas about that. It seems that it only stalls agter the moter has warmed up and I have driven it ten or fifteen miles. I have wiggled the ignition switch when the engine misses and it has no effect. I am wondering about the ECM control relay, and also the fuel pump relay. Is there a separate relay for the high pressure pump? I appreciate any light you may be able to shed on this intermittent problem. I have spent a lot of doe replacing things that did, nt need to be replaced. There are no trouble codes showing up. Thanks for your time Mike.
Sincerely, Bob