Air in Fuel System with Video
 

https:youtu.b/nGiGYQ0zw6s1983 300SD, 206,000 mi.

I have changed all fuel lines including tank. fuel strainer clean, new injector nozzles and balanced (Greezer), rebuilt lift pump (Greezer), with new primer. I am running engine in video from a gallon jug to eliminate everything back of primary. I need to stop this air from getting in. I have installed a FAII to see bubbles in return. Funola Air Ingress Indicator. Please Advise.https://youtu.be/nGiGYQ0zw6s

Where are you seeing Air. It is common for the Plastic Primary Filter to have an air bubble in it.

Also you did not say if it was running OK or not.

See video it is return line I have installed additional filter.

Is that relevant? If those filters tend to keep an air bubble in them, and you are pushing return fuel ipunder pressure into there, no doubt it will bubble up. Ever look at the diesel in the filler neck when you fill the tank?

I’d be more interested in getting some new hard lines that you can see through clearly and observe them.

It's normal.