[72lb4x4]

I'd guess you have a combination of problems. Making the potentially invalid assumption that GM ebrake designs will be similar, my experience is with a 71 Camaro.

I needed a new front cable, and various hardware including the spring under the car. Several bits were missing so I had to figure out how things went together.

After assembling, adjusting and messing around with it I shortened the spring to make the pedal return the way I think it should.

There's also a small spring in the pedal mechanism that keeps the ratchet action working as mentioned by another poster. It doesn't sound like this is the problem.

I'd get under it, look at thinggs wgen the brake is released, and then look again w/ the pedal down. You may have a stretched cable and missing spring, or missing guide hook(s), etc. There's probably at least a guide hook on the pass. side to make the cable run sort of straight back on that side.

Try to find a drawing in the manual, or pics of what the cable layout is with any springs or hooks under the truck.