Stop replacing parts for now and try the following, no cost to you, just 30 min of your time.
I had about the same problems in my '92 745, with intermittent stalling and I solved my problem with the following hints:(which I found in the FAQ's)

1) clean and tighten the electrical connectors to all the sensors, ie AMM, O2, ECT, etc

2) clean and tighten all ground connections, specially FI grounds at intake manifold

3) clean and tighten FI connectors at + side of battery(mine were corroded with lots of green powdery stuff at the crimpers, not easily noticeable).

I also replaced the crank(rpm) sensor since the old one was the original and the insulation crumbled when cleaning the connector.

Good luck
--
John '88 240, '92 740 Tampa Bay