My truck eats cps's!!!!

[wdillingham]

Hi! brand new guy here hope ya'll can help! I bought a 97 f350 with a 7.3 psd in it in november. everything was ok for a while. Then the cps went out. put in a new one. It lasted about a month. OK so they are prone to go out...put in another one. It went out. Ok made the plunge and bought a ford one it lasted about a month and a half. put in another ford suffix b one and it lasted about 50 miles. I went to the store the other day and had to burn another one just to get home. So I called a guy in the atlanta area. he said that the plug should have one pin that is ground one with 5 volts and the other is a signal return. I have one pin with .02 v the center one w/5 v and the other end on with battery voltage 12.4 v He said that this didn't sound right and that I should bring it to his shop. He is 75 miles from me. I am afraid to drive theis thing accross the street!!! when I crank it and it is running the pin w/ 12.4 volts goes down to 7.3 to 7.5 What could this possiably be?? Is the pcm bad? Oh yeah the voltage origionates form the pcm and not the harness. Thanks for your help