My 240 DL 1989 just this weekend started giving me starting problems. This wknd started extremely roughly and actually died once at a stoplight. Now today, it wouldn't start at all. Thought it might be a dead fuel sensor, as my fuel gauge read above empty not by much(I feel it performs best with the least weight, aka I'm cheap).
So, put 1.5 gallons in the tank and tried again.

It still wouldn't start at first. After 3-4 more tries and pumping the gas pedal, it finally started, but extremely roughly again. It was wierd, too, it started kinda on the keys being rotated back to the initial position. Once started, it ran extremely roughly. I did not drive it anywhere as I didn't want to get stuck and have to call AAA.

That's the events today and here's the background info:
About a month ago:
-replaced the fuel filter(told it wasn't prob necessary but its been 3 yrs having car and I dont know last time it was done)
-Cleaned out air mass meter(gently) and air intake manifold and gasket
-new air filter
-replaced 02 sensor

Was running noticeably better after this work, more power and no hesitation upon starting(was hesitating for a month or two before doing the repairs)

I personally think its the fuel pump. I hope its the external one and not the internal one. External I could change pretty easily as doing fuel filter wasn't too bad. Don't ask why I didn't replace both at the same time.
Anyways, thanks for reading my long messsage and any assessments are appreciated.