Need help with identifying problem

97 k1500 Silverado. 5.7 vortec.  So I have an interesting
problem.
Bought this truck with no dash lights, replaced the ignition
switch and she was running. No codes.
My gear indicator light, abs light and ebreak light all flicker
and cut out under hard acceleration and bump, like a
shorting wire, but it also will do it sitting still with the engine
off and the key in the run position.  Another symptom, when
the gear indicator light is off, sometimes the climate
control will not work. If I try to start the truck while the
climate control is on but not working then I get a dead
vehicle, no crank, no click from relays, only the hum from
my fuel pump.
Also no back up lights.
I've replaced my neutral safety switch and still no backup
lights. My running lights seem to flicker with my climate
control... im mystified.