Truck Won't Run

[Bunkythe3rd]

I am having an issue where I go to turn my truck on and the motor will start when on the starter but when the key returns to the run position I lose spark. The motor then spins down to a stop. I put a timing light on it to verify there was no spark.

One other thing to note is, I was having an issue with the motor stalling out before not starting so I did replace the carburetor during this time to rule out fuel.

Now the stuff I have replace. I have replaced the ingnition switch and the ignition coil. What else should I test or replace?

The fact it is running when on the starter and actually over runs it has me stumped. I have attached photos of the switch and distributor just in case it is something as stupid as a wire is missing.

Thank you to everyone in advance.