Ok, First off i know there are alot of threads on this and i have searched hi and low with no luck. Here's the issue, 84 Z28 L69 700r4 starts when wants too better when cold but still random. now i have checked all the wiring no problems i only get 9 volt to the purple wire when it does this.
New ignition switch and NSS stilll same prob this is not computer controlled anymore Hei and carbed now, first thing i did was hook up a wire to the solenoid so i can start it on the battery when needed wich always works so starter is good. the other day i hooked up a push button switch to a Constant + from where all the under hood relays by the brake booster used to be and then to the purple wire in the harness. wich worked fine untill today, drove awhile and it would no start again but push button worked fine then one time the push button was dead also. so i jumped it under the hood, good thing i had the wire still there lol. anyway i am now thinking that the issue isnt with the ignition wiring its with the positive coming in somewhere. so any suggestions on where to start? also battery good and cables and grounds including body engine and batt.
also the push button wire is 10 gauge so its not an issue.

 

also there is no start enable relay as i searched every where.

 

So trace the power wire from the Ign switch and find out where 12V turns into 9V.
May be a bad / loose / dirty connection somewhere

 

I finally found what the problem was. positive coming from the solenoid i pulled the entire engine harness out and after removing some tape i found that someone had removed the fusible links. they cut the wires high enough the splice was in the tube that shields the wiring from the exhaust. anyway they used cheapo crimp couplers. so i'm assuming that between being oily, and the heat caused them to expand enough to lose partial contact resulting in the voltage drop when hot. so i replaced the fusible links used steel crimp style couplings and then soldiered them, so far so good. so much easier to do with harness removed.