Distributers wear out, check the bushing by shaking the shaft and watching the points gap for any change, also ground the block to the frame if their isnt one there. Fuel pump pressure at higher RPM, T in a pressure gauge and a vacumn gauge and go for a ride. Bad thing is when you find it your will feel like a "Blooming Idiot" for overlooking something so simple. Good Luck, we have all been down that road a time or two, it;s called learning.

You Learn more Listening than Talking