Loss of acceleration

[38Feet]

I have a 2003 Ford Excursion w/6.0L. On acceleration up hills, it will sometimes lose power and the more I accelerate, the more power it loses. Puffs of black smoke come out of the exhaust and the truck jerks when the puffs of smoke come out. It also makes a sound that sounds like puffs of air when it's jerking. During this summer heat, I can get it to do it more while trying to accelerate on the highway when both a/c units are on in the truck.