Random stalling

My car will run anywhere from five minutes to two hours and it dies. Sometimes it will start right back up, but most of the time it has to set for several hours. I have replaced the ignition module five times, CPS once, plug wires and plugs. All this started when it got over-heated once and split the radiator due to the cooling fan not coming on. This caused the check engine light to come on and caused a high idle. I found there was no ground signal to the fan relay so for a temporary fix I added a ground to the relay so the fan would come on with the key. I also replaced the fuel filter and checked fuel pressure and it is at 45 psi. When it dies it has fuel pressure and spark, but now it has to set a while before it will start. All connections have been checked. I ran out of ideas so I sent it to a well know shop and he hooked it to his Snap-on scanner and noticed the charging voltage read 17.5 volts so he probed the battery positive at the alternator and it read 13.6 volts and when it dies it is getting injector pulse. He said there had to be something wrong with the PCM. I got one from a known salvage yard and he replaced it and everything checked out great and the check engine light stayed out. I pick up my car and drove it about sixty miles and it died again and would not start until it set overnight. The mechanic checked it out and said the PCM feels hot when it is running so it may be bad too. The check engine light did not come on this time so there was not any codes. I have spent $300.00 on this car and now I am afraid to even drive it one block. Any and all suggestions would be greatly appreciated.

Thank you,
Michael "HARPO" Williams
harposrepair@yahoo. Com