Air_Gap

This has puzzled me for a few days now. I had just put in a new gas tank and when I started my truck up it idles up and down, but only at idle if you step on the gas it acts normal. I ran diagnostics on it and even the scanner couldnt find a problem, the tps was at .86 at idle and the available range is .20-1.0. Now if I take off the map sensor vaccum line and plug it it idles fine for awhile then just decides to quit, it also quits after idling up and down for awhile too. When I hold the pedal up out of idle it runs fine. It gets fuel, the scanner says the electronics work fine, I even went through the intake manifold twice looking for vaccum leaks. I have no idea what could possibly be wrong if anyone has any ideas please throw them at me.