1985 1.6 NA diesel missing when going up hills

I have an 85 vw diesel that is missing really bad when going up hills. pull over let it sit, clears up tilll next hill, IP timing good, engine timeing good, good compression, worse when engine cool, getting worse over time. IP return lines clear, no air leaks, ??? I’m stumped

Fuel filter?

Fuel Filter good/new.

does this happen even when your fuel tank is brimming full? I know you said no air leaks but I am still wondering if you are sucking in air bubbles when you go up a hill and the fuel flows to the back of the tank.

if thats not the issue is it missing on all cyl when goign uphill? I’d try some diesel cleaner/lubricant (the guys that make diesel911 in the red bottle make an excellet cleaner).

Yeah, happens at all fuel levels. Have been running lucas fuel treatment. new injector nozzles too. have new injectors coming this week, but am skeptical. yes, starts to miss on all cylinders when going up hills

Sounds like injection pump pressure might be low or there might be a filter sock on the fuel inlet inside the tank that is plugged up, starving the pump…