302 well will not start, With timing light as soon as spark occurs will start, spark can be haphazard then suddenly starts working. sometimes runs great for a little while. I am thinking distributor pickup or ignition module? Any ideas? Coil has been replaced. Cap & rotor are ok.

 

I suspect a bad ignition module or a bad pickup in the distrubutor. I will check them out following the manual...

 

The connector for the coil was faulty and had allowed the plus side of the coil to push out of the holder. The + side was just touching. Pushed it on and truck operates normally now...no parts replaced.