Starting problem

[joshclift]

I have a 78 gmc jimmy with a lot of new stuff. Sometimes when I go to start the truck i turn the key and the truck stutters then loses all power. I turn it again and still nothing, I get out and knock on my starter and move the wire around, which is brand new, and then it starts. Sometimes it just has zero power and when i come to red lights at night my lights will start to flicker at low idle or my radio will cut off then restart. I replaced the starter twice, alternator, cables, idk what else to do.

 

[Wes Harden]

classic loose connection at main start lug. Disconnect battery, and make sure the battery cable is tight on the main starter lug. You should have 2 smaller wires connected to same lug, these are fusible links. check them they can melt through but still have a connection. The fuse links supply power to the cab, ignition, and lights.
Let us know what you find.
Don't beat on that starter to much or to hard, or you maybe replacing soon.