at a guess the brakes have still got air in the system and need bleeding properly
Check you brake fluid and lines. It may be as simple as bleeding your brakes.
Having ABS does not change how you bleed the brakes. Bleed them as you would if it did not have ABS.
Bad brake booster.
The power brake booster is leaking vacuum and that makes the engine die when the brakes are applied. Replace brake booster.
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?
the cruise control is broken....
Usually the fuse is going bad.
yes
it could be a ghost
YES. That would be a direct swop.
A bad spark plug(s) can do that.
A 1977 Chevy pickup truck would have rotors in front and drums in the rear