96 Ram Van 2500 3.9l smoking, no power

I am hoping someone can point me in the right direction. I took the van with 120,000 miles on it on a 400 mile trip. The check engine light came on around 120,000 on the outbound, and I attributed it to a preprogrammed time for engine maintenance. It cleared around 120,300. The van ran great. On the return leg, it started to smoke around 200 miles into the trip. A tan/black smoke from the exhaust. The oil presure stayed good, engine temp was good and battery was good. When I came to a hill, depending on the angle, the smoke would get worse, and the van would decelerate, start at 60, finish at 25, even with the gas pedal to the floor. It ran terrible below 35/40, with some stuttering above 50. Slow to accelerate up to to 35, but then take off.

Thanking you in advance for your assistance, Ralph

sounds like you were running rich if you had black smoke coming out of your tailpipe. If you can, go back and retrieve the code when your check engine light came on by turning the ignition key on/off 3xs ending in the "ON" position. The light will flash; for example if it flashes twice then pauses and then flashes another 4xs, that's a code 24. From what you are describing it sounds like you have a problem with either your throttle position sensor or your MAP sensor.