This is re a 1990 1.6TD JX. We seem to be in danger of getting stranded on holiday in Germany

Seen a couple of other threads on here with similar symptoms and wondering whether this a problem with a lack of fuel getting to the engine. Fuel filter was replaced < 5,000km ago. Both fuel lines going to the pump have a mixture of air and fuel in them (with the engine not running). Normally van starts pretty much straight away but once this issue occurs it takes a lot of turns before it splutters into life. It goes along the autobahn no issues at all, just when we're in a town that it loses power and stalls.
Any thoughts for anything I could do here with limited tools (pliers, screwdriver) to try and get to the bottom of / fix this?
Many thanks
Andy