a/c ford 5.8 stops

Sounds like the loss of power cycle is activated. You may need a tune up. Check wores, plugs, Maybe even a coil is going. Fords do this to give you the power you need. The clutch deactivates to lesson drag on the engone.

Also keep in mind...at WOT (wide open throttle) the AC will disengage. A majority of vehicles do this for 1(more power), 2(less wear on the compressor), 3(less change of over pressurizing the AC system). Some cars will cut the AC in excess of 4k rpms. Most cars will cut the AC if the ECU reports a high engine load(in need of a tune up) or if there is a misfire (again, to maximize performance).

What is happening is the engine loosees vaccum during acceleration and comes back the vents are controlled on the older cars trucks by vacuum so when it goes away from the heater it moves to the defroster position and moves back as it comes back in

Probably should check the vacuum

For leak smoker wors best but very expensive use carburetor cleaner and spray around and the engine will change tone if it pulls into a leak