Question about truck

I have an Ford Explorer Sport Trac and it has about 100 thousand miles on it. The check engine light just came on and now when i go uphill it takes a long time for the car to pick up speed. In fact, it almost sputters at times. Going on flat surfaces or downhill is fine. Any ideas?

The Check Engine light is where to start. Some parts stores like AutoZone will pull the codes for free. Get the codes pulled and record the code number. This will something like P0XXX. Report back with the code(s), and then we can see if we can offer advice.

Tester

It could be starving for fuel from a dirty fuel filter; or, bad spark plugs, or dirty air filter. Change those parts, erase the codes (usually, by disconnecting the battery for a couple of minuets). Drive vehicle. If check engine light comes on, have it read at an auto parts store (free). Bring the codes here.