My 2000 GMC/jimmy suv starts up but doesn't respond or rev up whenI push the accelerator pedal

SOURCE: engine stalls when acceleration

sounds like poss throttle pos sensor prob./ could also be problem w/fuel pump not pumping enough fuel at high speed. poss fuel filter clogging also. have someone check pump pressure.

SOURCE: 1995 gmc jimmy, bogs down, rpms jump up and down

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SOURCE: 2000 GMC Jimmy won't start

i had the same problem and replaced the fuel pressure regulator. Cost about $45 at advance auto store or about $90 at napa auto stores. Once i replace that my truck started right yup and runs like a champ

SOURCE: Brake pedal still goes to floor 2000 GMC Jimmy

It's very possible to be the master cylinder, the o-rings on the piston could be worn, letting the fluid seep back through instead of getting full pressure through the lines. Could also be the brake booster.
Try changing the master cylinder first, which is cheaper and easier, and see if there is a difference, you'll need to bleed the brakes again.
To check the booster,
With the engine off, pump the brakes until the pedal is hard, then hold pressure on the brake pedal and listen for air escaping, or the pedal goes slowly to the floor, Do that after the master cylinder has been changed, at least that will be eliminated.

Testimonial: "Hadn't thought about the O-rings on the rod thanks for the idea. Great Idea Thanks!"

SOURCE: How to uninstall a blower motor on a 1999 GMC JIMMY

Yeah if you have to tap on it, then that means the brushes in the motor are worn out and you need to replace it. The blower motor is behind the PCM and Coolant Overflow bottle. If you remove these then it will give you better access to motor. You'll have to cut around housing. There should be a groove already there for you, just make sure you don't cut all the way around it. Once you open it and get the new one installed, you'll have to use caulk to seal where you cut it at.