It could be a bad brake hose that has collapsed on the inside. An easy way to check it is to pump the brakes a few times then go to the bleeder screw on the right caliper. Open it up just a little and if brake fluid squirts out (not just slowly leak out) then the hose is probably bad on the right side. If it just runs out, I would try to bleed the left side again.
air still in lines. rebleed
The power brake booster is leaking vacuum and that makes the engine die when the brakes are applied. Replace brake booster.
Having ABS does not change how you bleed the brakes. Bleed them as you would if it did not have ABS.
Pneumatic schematic in the air brakes in any type or build of truck all work in coordination with each other for smooth driving. The brakes would not be able to smoothly stop without them.
Check you brake fluid and lines. It may be as simple as bleeding your brakes.
Your vehicle is equipped with abs and anti lock brakes, when applied hard enough the system interprets it as a panic stop and pulses the brakes to prevent lock up and skidding.
Friction
at a guess the brakes have still got air in the system and need bleeding properly
The front rotors are out of round are warped. Turn are replace rotors and be sure to replace the brake pads even if thay look good. I would also check the tie rods too.
Does the truck have stock discs? Why would you want to switch the discs back to drums? Does the truck have stock discs? Why would you want to switch the discs back to drums?
I would say a vacumn leak. Check hoses, measure vacumn with running at idle and at idle when brakes applied. This assumes you have power brakes and it idles well without the brakes applied. Please make sure that the clutch is working properly... Does your clutch work properly?
Usually the fuse is going bad.