Awhile back I got a 745GL for my daughter. It had a few issues, notably a disconcerting habit of stalling when you hit the gas, or just shutting down when cruising along. It also would always stall if you hit the brakes moderatly hard. I was thinking a loose connection. I posted here looking for ideas and pulled the codes, which indicated loss of battery power and Idle solenoid bad signal.
Thrashed around awhile looking at the idle solenoid and throttle switch but from looking at the wiring diagram i realized that loss of battery power would remove power from the idle solenoid, so probably the computer was being fooled there. I checked and changed the Radio interference relay to no avail. Was looking for a junction point indicatd in the wiring diagram but was informed on the BB that this was a "green book joke". So just for something to do I checked the water level in the battery....hmmm really low. Filled it to the proper level. At first no change, but within about 30 minutes of driving the gas/braking stalling problem disappeared! Apparently the sloshing of the electrolyte in the battery (a Volvo brand) was causing momentary power outages. Hard to believe but .........

However, the car would still stall when cruising, always sometime between 5 and 10 minutes of a cold start (this would be about the time I got up to speed in the outer lanes of the interstate). Got good at just rolling along in neutral and cranking the starter. Would usually restart in 30 to 60 seconds.
Back to the wiring diagrams. What components could fail when cold and be supplying power for the fuel system (the tach was working when it would stall so I concluded it was a fuel system failure). What the heck...swapped the LH fuel system relay (the white one in the center console) to my other 745. Woops! Now the 89 745 had the problem and the 90 was fine!

Never would have thought. The relay literally always fails only once for less then 1 minute sometime in the first 10 minutes as it warms up.

Stange stuff for me........
--
744 & 745 16v 4+OD, 245 SE auto, 242Ti 4+OD, 745 8v auto (new), 245DL auto parts car