So I'm have a problem with my 1990 volvo 240dl, a few months back I couldn't get my vehicle to start on an incline or after refueling even on flat surface. It went away a few months ago and it didnt happen but a few times but it seems to be coming back now, I'm going to replace the fuel pumps and filters, but is there any other ideas just in case?

 

Before you go replacing fuel pumps, I would test them first. The main pump lasts virtually forever if you keep the in-tank pump working. My '90 240 still has the original main pump and it is quiet as ever. This site has a nice explanation on how to test:

In the Tank - 240 Volvo Tank Pump and Sender

 

couple of thoughts for the early a.m. - maybe the fuel pump relay is on its way out and/or might be some vapor lock happening.