New member from Iowa needs help

[jschmidt679963]

Hey all. I'm new to the forum, but not new to working on cars. I was a mechanic for many years at independent shops, and GM dealers. I am usually a GM guy, but my daughter wanted this Explorer, and i couldnt pass on the deal.I just purchased a 2004 Explorer for my daughter. It has the 4.0L "K" motor in it. The truck didnt start when we bought it. The previous owner thought that the fuel filter was clogged. I have since proven that wrong. I started digging into the crank / no start condition. Fuel is good. Checked spark. No spark from coils. Checked power to the coil pack. Have 12V at connector. Checked resistance of coil primaries and secondaries. All within tolerances. Started doing a little more digging. Found that the ground side of the coil control is controlled by the pcm, but it needs the crank signal to pulse the gnd. Started checking the crank pos sensor. I found that i only have 1.5V at the crank sensor connector after replacing the sensor itself. I got frustrated with the truck and disconnected the battery negative cable and walked away from it. A week or so later, my 2 sons went out, reconnected the battery and it started right up and ran. I walked out there in disbelief. Started the truck and it ran until i shut it off. I went to start it a little while later and no luck. Back to the crank/ no start condition. Im thinking the PCM is heating up internally and breaking a connection. Anyone have any thoughts on this? If anyone has a wiring diagram or pin-out for the connectors to the pcm, i would really appreciate the help.