Motorboating 245 Volvo

I have a motorboating 1990 245 Volvo. When it gets into this motorboating the engine races and then drops and I can only go 20 mph jerking the entire time. The gas filter and gas pump have been replaced with no change in the condition. It will start in the morning running just fine. After about 5 miles it goes into the motorboating and I have to get home at 20 mph max. My neck muscles are getting stronger, but I dare not take drives across town. Suggested solutions have included (1) changing the gas filter in the tank, (2) injectors are partially clogged, (3) an air bubble in the cooling system , (4) dirt in the gas tank that has caused the replaced filter to partially clog. Has anyone else have this problem ?

Older 240s actually had two fuel pumps–one in the rear fender well, and one in the gas tank.

Based on your post, I am assuming that only the one in the rear fender well was replaced, and I think it is very possible that the one in the fuel tank also needs to be replaced.