runs for about 15 mins then dies

[whiteboy_77_77]

Hey guys i justpicked up a 96 f250 7.3L that didnt run when i got it,
anyway i put a new cps and glow plug relay in her and she flashed right up, now the problem is when its cold and i start it and let it idle for about 15 mins it will just shut down like i turned the key off, some times it wont fire back up unless i give it about 1/4 throttle. if im in the truck and keep it above 1500 rpm she runs just fine and dont miss a beat, if i bring it up to 2000 rpm evey now and agian it acts like if someone turned the key off for a split second and then keeps on goin, does this maybe once every 10 seconds if i bring it up to 2400 it will act if someone is turnin the key of and on really quick once every 2 seconds 2500rpm and up it dont miss a beat once its, warm at an idle it will run like a top for about 15seconds then shut down but fire right back up agian, runs smooth as silk but then is just like some one turned the key off. any ideas
Thanks Mike.

[whiteboy_77_77]

So figured it out , ended up bein the new cps was crappin out when it got warm , Thanks for all the help,
I guess the 6.0L guys are the only ones who at least try to lend a hand.