Truck has me at a loss
 

2002 f350 7.3L ..... Out about a month ago and was driving down the road and the truck just shut off like you turn the key off .. Figured it was the CPS since it started right back up after it cooled down .. When and got just an after market one from auto zone, the light gray one ... What it in and everything was fine for a week or so, Drove the truck 3 or 4 different times .. Then it started doing it again .. Heard some bad things about the light Gray one, So went to ford and got the new dark Gray one with the purple o ring .. Put it in, And the very 1st time I had the truck out, It's still doing it ... Are there any other things that seem like the CPS but isn't ... I'm beginning to think it might be the IDM now .. if I switch out the CPS to the one thats cold itll run for a while, then it will quit, put the other one back in after it cools and then that one will work for a while, then quit ... I'm at a loss ... any help Or any suggestions would be greatly appreciated, Winter is here and I need my truck, But right now I can't count on it ..