wiring

[86c20]

ok so i have a gremlins at work. i have a 85 k30 with the 6.2 and some time she wont crank at all. can drive it all day fine then she will not turn over. thought that something was getting hot so left the key on for 4 hours with the tunes on and she started fine drove it first thing in the am after stiting all night no start so its not some thing hot it seems. have done the wiggle test with no luck and i am just out for my mind right now. does anyone know what it could be or have the wiring dieagrams for it? any help or what to check would help also the clucth switch is by passed and has voltage on it when she dont start that is all i know. thanks, later mike