1982 K10 6.2 Diesel

Looking for Help

Just bought this truck, drove fine home (about 80 miles).
Next day started acting up. stalling when driving to the point it wouldnt start anymore

what I have done so far

1. replaced the primary and secondary fuel filter
2. replaced the manual fuel pump
3. had to replace return lines at 2 of the injectors ( tore by accident)
4.) got any air out of the line by removing the return line on IP and blowing the air out until fuel came out of the secondary fuel filter line

at this point I can start the truck. IT idles until I turn it off (let it idle for 90min the other day)

when attempting to drive it may last five minutes before it stalls out, sometimes it will start back other time it runs the battery down and wont start

seems to have lower than normal power when accelerating also
notice a vibrating noise at the bed of the tuck (not sure if this related)

This does have 2 tanks, I currently only have 1 tank connected so I can bypass the tank selector.

any suggestions as to what the next step may be on this

one other thing , gas gauge doesnt work either (guessing the sending unit for this part)