Fuel problem 1985 380se W126

Hello everyone, my name is Dana, my husband Jerry and I love our older Mercedes cars. My gem is experiencing problems that we just cannot figure out, any and all help will be so greatly appreciated. Fuel problem started with car hesitating here and there on take off. Fuel relay went, we replaced it, was running fine, then she would stop running, like it ran out of gas, had the fuel filter replaced at the local shop, it was the original filter, on the way home she was hesitant and then picked up and ran fine, like no problem at all. Went for another test run and she started hesitating so bad, got her back home, where she quit running, she would start, run for a second and then quit again, then she wouldn't start at all. The next day she started fine, ran fine, took a short run, started hesitating, made it back home, where she quit running, tried to start her, she would turn over, run for a sec, then quit, then she won't start at all. Let her sit for a day she starts right up and then repeats the same symptoms.
Car has only 149K and this is crazy but we had no problems whatsoever with her running, then we had to replace the water pump when I had the car out of town, a friend of the people I was staying with(for a funeral) replaced it, a very knowledgeable mechanic, boy that was a job, anyways she made the 3 hour trip home no over heating, but she would hesitate when trying to get up to speed. Three months ago was when we had to replace the fuel relay when it went bad and the fuel problem just started getting worse, went onto the forums and the cheap fix(we live off of SS retirement and are raising 3 grandchildren) was the fuel filter, replaced it and now the problem is worse and listed above. Its like she has a fuel gremlin that we can't figure out and can't afford a shop to try and figure it out. She does have spark, we made sure it wasn't an electrical problem. We would appreciate any help and thank you! Sincerely, The Gates Family VIN WDBCA32C2FA143214