How is car running now friend has similar problem?

 

Sorry about taking so long to get back to this but, work is well, work.
Anyway I think it was algae and not oil.
What I ended up doing
Installed new filter screen with new fuel line and o-ring
Flushed the tank with Simple green ( very small amount used )
Looked like gray sewage water when emptied out
Rinsed and drained the tank 4 or 5 time until water was clean.
After I let the tank air dry for 2 days I put about a 1/2 gal of diesel in and swirled it around and dumped into my waste full tank.
I flushed the sending unit out with Brake Cleaner, it was as gunked up as the filter.
I was able to get most of the brake cleaner out and was got some Marvel Mystery oil down inside. ( I used a small syringe )
Re-installed everything and for good measure replaced both fuel filters.
The car is running great. At first the fuel gauge went crazy a couple of times but other than that everything went fine.