I have changed both fuel filters and air filter, adj valves, with little help, But when car runs good it runs very good! It seems to happen when you just start off, and gets better after about 10 miles On a trip to Boston car car ran great on way there ,on the return trip I stoped and shut the car off , and when i started back up it had a hard time making it up hills! the next day it ran fine? Could it be filter in fuel tank?
Jim

Only way to tell is to take the tank filter out and inspect it.

Run the tank almost empty. Remove the fuel hose from the fuel line and let the remainder of fuel drain. Screw out the filter.

Since the filter is more of a screen than a filter, you can easily see if it has dirt embedded in it. If it does, clean it in a solvent and put the filter back in the tank. Its not necessary to replace the filter unless the screen is broken.

P E H

When I cleaned the one in the tank on my 82 SD I found the vent was plugged, the screen was fine. You may want to check the vent line as long as you are working in the area.

Tom
82 SD
86 SDL

At this point it looks like vacuum at ignition switch is leaking , Last night it ran well going to work but not great going home , so I moved key slightly and it was like i turned on the turbo! I going to replace ignition switch asm this weekend . Thats not where i thought problem was!
Jim