Clogged fuel filters would more likely affect high speeds,

Poor acceleration from stop is very likely to be cured with an ALDA adjustment to richen the fuel mixture. Every one of my cars has needed it and wow, does it make a big difference.

Do a search here to find out how. It's VERY satisfying and easy. You should be able to throw gravel from a start on a dirt/gravel road.

While you're setting the valves, check your timing chain stretch by lining up the mark on the rear of the timing gear with the notch in the cam support. It's on the drivers side rear of the timing gear. With this lined up very carefully, you will have a reasonably good idea if your chain is stretched more than 2 degrees. I think performance is seriously affected around 4 degrees measured at the crank.

And checking your throttle linkage to make sure the arm on the IP is up against the stop when the pedal is fully depressed is a good idea too.

Best Wishes,
Bruce McCreary
(2) '85 300Ds, '83 300CD