I am a very blessed man, and also a very humbled man. It would seem that during a 2nd round of swapping Air Mass Meters in the car earlier, I forgot to clamp the accordion hose back onto the AMM after re-installing the original. Since then, I must have found and fixed the fuel injection system problem and not realized it because the AMM was preventing the car from running. So, while I can't pin-point what the original problem was (it's fixed now and has been for a bit), the 2nd problem was created by myself.

I hadn't yet disconnected the AMM wiring since swapping batteries last week, so I knew the 1-2-1 code for the AMM was a start in the right direction. Peering into the car, I found that the accordion hose was up against the backside of the AMM, but not clamped on. While they appeared to be connected at the top, they were not, and had a gap opening at the bottom of the connection from the housing and hose being tilted away from each other slightly. After clamping it together, she fired up and ran (on the auxiliary fuel system), then I transferred her back to the cars own internal fuel system and she started right up as well. I also took the time to clean the AMM wiring connections with a dental pick. I could not get the terminals to release from the connector housing in the cold and didn't want to force them and possibly break the connector (I have another, but it's buried in the storage unit). I need to re-pack the connector with dielectric grease, which seems to have insulated it well from corrosion as everything looked ok as I was cleaning it.

Here's a quick list of possible culprits that may have fixed the original stalling issue that I've done since the 2nd round of AMM & ECU swaps where my mistake occurred.
- Replaced in tank fuel lift pump (should flow through even if bad and car has a full tank of gas).
- 2nd round of Fuel Pressure Regulator swaps.
- Cleaning every ground connection terminal in the car relating to the fuel injection system and ignition systems per the 1993 240 Green book wiring diagram shop manual. I did a few of them earlier, but did EVERY one this time.
- I may have swapped the fuel pump an additional time as well. Could have been 3 or 4 swaps total during this ordeal. (first spare pump was seized, second and third pumps ran but stalling problem not fixed, fourth had a small leak in the housing that sprayed gas, final pump is on the car and may be the same pump from 2nd or 3rd swap)

The original symptoms were a loss of power while driving, and the car could barely keep itself running at idle. The problem was intermittent at first, increasing in occurrence, and then required a tow home finally. I'm hoping she's fixed but the proof will be when we have it on the road for a long drive.

It might be a day or two before the car is back on the road, there are a lot of things to be reinstalled that were taken apart during the diagnostic and troubleshooting stages. (like trunk interior, the exhaust system, lots of panels around the front passenger area, etc).

Thanks again for the help everyone and a special thanks to Art & Dan as well. I really appreciate this community and the assistance. God bless,
Fitz Fitzgerald.