https://youtu.be/5drHHBgt5RE

Im trying to figure out what is wrong. Seems to run good after it sits for a day, it will idle good and drive ok. After I go a couple miles or rev the engine up after a few minutes it gets worse and worse where the engine will die. Ive replaced the fuel strainer, fuel filter, lift pump, govener springs, overflow valve. The engine was rebuilt, bored .40 over and balanced and timing set at 16 degrees approx 100k ago. Ingection pump was replaced approx 20k ago. Thanks for any help! Also It seems like it runs smoother when i flip the valve to drain the fuel filter. When I do this no fuel runs out momentarily like air is escaping, then after a couple seconds fuel spills out. Might I have an air leak? How do I track it down?

 

Also I deleted the fuel pre-heater and put the strainer on with a new gasket. And put on a new fuel hose elbow from the prefilter to the lift pump. Again thanks for your help guys.