2000 Ford Excursion Cuts off when gas pedal pressed

Does it spit and sputter, then gradually die, or does it simply cut out all at once? A few things to check either way: mass air flow sensor, throttle position sensor, and crankshaft sensor. If ou could post back with the response to the question, we can go a little deeper if needed.

It cuts off all at once

You may want to check the Throttle position sensor first. Since it happens when the throttle is touched, it may be shorting out.