Mercedes: Loss of power on hills in a 1985 300td, water in the fuel, pedel

Question
Our 1985 300 TD slows way down on the same long steep hills it took the week before. Transmission steps down when gas pedel is pushed hard, yet we still go slower. Ideas? Things to have tested?  THANK YOU, Steven

Answer
Steven,
Am I correct that is a non turbo diesel station wagon? Do you notice black soot smoke coming from the exhaust during these hill climbs. If so, you may have a clogged air cleaner idd filter. Or the injectors are clogged, or you have a fuel delivery problem. Or Your Canister  fuel filter, or you may have some water in the fuel.
Check the replace the fuel canister filter. Get some diesel fuel cleaner and put it in the tank. Biodiesel is a good cleaner.
If after you have done all of the above, I would look a running a fuel pump test to see if it is supplying enough fuel to
Good Luck,
Keep us informed on how it goes
Rob