83 300D starting issue

I've got a 83 300D with about 230k that has an issue starting up.  About 2 weeks ago was when the problems began.  It was incredibly cold, and my fuel gelled up I believe(but i still got it running in the middle of the night I used iso heet/bad or good?).  Ever since then I have been having issues starting it up.  It will start in warm weather, but it will crank a lot before it turns over.  I initially thought it was the battery but it wasn't; full charge.  Then the filters; both are replaced same result.  Now I am beginning to think its the injection pump.  When i first get it started, It takes a while for it to "warm up" if i throw it right into gear it will stall out on me.  Anyone out there have any idea if my injection pump idea is right?

Have you flushed the system?

First off , Id check with a test light that the glow plugs get voltage. Assuming they are, disconnect the cables from the glow plugs, 8mm IIRC, and measure resistance on each. About 2 ohms is good, infinite is bad. I had to change all of these on a similar MB a month ago.

Next, I would improvise a mini fuel tank, right near the engine and pump to, hopefully, eliminate any clogs or restrictions in the lines or pick-up tube or supply/lift pump. As these things are 25 years old now, who knows what may be lurking in those tanks?? Your stalling seems like a inadequate fuel supply problem, so rule that out before checking the high-pressure side and injectors.

I had the same problem it was the glow plug relay .

Terry