Yes change the filters. Follow the procedures described in the manual to prime the filters. The lift pump is on the SB side of the engine
about mid engine just above the pan level. There you'll find the hand primer. If it's not priming up you may have a faulty lift pump.
I've seen this during rough weather
when there's not enough filter coverage (IE at least 2 Racor
style filters). Shaking up of diesel
will make it foam and will take a few days to level out again. Manual priming of the engine with the lift pump should fix this issue.