OBD DTM 3 does apply to your 240. Where you see mention of that not being for all 240s they're talking about the older LH 2.2 systems without the OBD system and diagnostic socket, which was pre-1989 B230F and pre-1991 B230FT. There was no 240 production 1996-on when OBD-II came into efect -no LED diagnostic socket under the hood, it has a special diagnostic connector, typically at the console.

DTM 3 is a very simple 5 minute test to help isolate your problem. No tools are required. If that tests passes then it's most likely your CPS, if it fails then it's most likely your system relay. I wish people would make better use of the OBD system as it is a valuable tool when trying to isolate a problem. The OBD procedures at least help narrow the possibilities and likelihoods before pursuing further diagnostics.

You're getting lots of suggestions here, so like Phil reminded you, try to focus on the basics that relate to your symptoms and work through it step by step.

You say you're getting spark and there is fuel at the fuel rail. Unplugging the AMM/MAF so you could try starting in limp home mode didn't help. You got the 1-1-1 code on both port 2 and port 6 of the diagnositic socket (I presume you checked both). All this very much limits the possibilities, such as it not being the fuel pump relay or ignition. That you are occasionally able to start suggests an electrical issue (either ignition or fuel side). I thought I recalled you've replaced the CPS in recent history and re-checked the CPS which is often behind a no-start, but in looking back at this thread it seems you haven't, so that remains a distinct possibility as noted above.

Whether you have a strong enough spark and adequate fuel pressure is another matter, but I would very much expect the engine to be either running very rough or coughing and sputtering during cranking if that's all it was -you can deal with later once fuel is getting into the cylinders. I'm slightly surprised that starter fluid didn't make a difference, which suggests to me either you weren't doing it adequately or that you actually do not have spark. If the injectors are actually being pulsed during the DTM 3 check, then I would suggest you go back and re-check that you are getting a reasonably strong spark on all cylinders. Please post back with your results. We'll take it from there if you're still having problems.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now