looses power after driving a few miles

my 95 s-10 four cylinder 140,000 miles starts fine and runs fine until i drive and it warms up really good, it starts to loose power and acceleration. when i stop and let it sit for a while it runs fine again until i drive it a while. what could be my problem. thanks

First pull any trouble codes. When was the last time you did a tune-up ?

I actually just fixed this problem on my 1992 S10 2.5TBI!!
Go ahead and change your Ignition Control Module. It's only like $28.00 at Autozone. Try it out. While your in there, I'd advise you to change your Distributor Cap, and Rotor. Very easy. And when you install the Ignition Control Module, don't forget to layer it with the special grease that comes with it. It should only take about Half Hour. Let me know how it goes. L8tr

check to see if your catalytic converter is plugged. how to do that is another matter. i had a 70's chevy 350 that someone had put some leaded gas in before i bought it and it would lose power and the manifold glowed red. i cut the cat. converter out and it ran better til it sucked a valve