Why does my ford f 250 triton v 8 cut out going down highway especialy going up hill?

I have k & n intake n it runs worse when I keep mass air flow plugged in

Going uphill puts a load on the ignition system, so I'd suspect a coil is about to go belly-up on you. Can you duplicate the miss by power-stalling the truck? This is an age-old method of inducing a load on the engine and the ignition system to find suspect plugs, plug wires, and coils.

Edit: This could also be a sign a of slightly lean condition, when's the last time the truck had the fuel filter changed?

I'd put money on a bad coil pack

Your check engine light should be on by now. Have it scanned. Most likely something that affects a sensor. With the MAF unplugged the computer ignores sensors and runs off a pre-programmed routine. Once the sensors are plugged in, one of the sensors is giving the computer bad information, causing the wrong fuel mixture. It doesn't mean it's related to the particular sensor you unplugged. It's a whole loop of sensors that make up the math used to calculate fuel mixture.

Maybe the air intake manifold has some problems, you could exchange a new one or add a turbo. Most cars cut out going up hill are because less horse power, and a turbocharger will handle this problem.