has a little problem pulling up hills

If this problem is occurring at freeway speed, then this is what may be happening - when you put you foot lightly on the brake on your 1999 Chevrolet S10 you are turning off the torque converter clutch lock-up. This allows more torque to be transmitted to the drive wheels. The computer should automatically turn off the torque converter when you apply more throttle. Perhaps this is happening slower than it should.

I assume you have an automatic transmission. If so, then touching the brake will shift out of torque converter clutch lock-up making it easier to pull a load. Try shifting out of OD gear and see if that helps climb hills.