Last Winter I posted about the then new-to-me 1990 740 GL and its issue on cold start when the outside temperature was below about 25 degrees F. It would always start right up, but at first would stall immediately if you touched the throttle. After maybe 1 minute at 25 or maybe 4 minutes at zero (long before the temp needle would move), when the engine had warmed just a little, it would run fine and otherwise ran great all the time. The suggestions from all of you were logical and I swapped or checked all of the following:

Coolant temp sensor for the ECU
Intake air temp sensor
Ignition cap, rotor, wires, and coil pack
Checked for vacuum leaks
Replaced intake manifold, TB and TPS gaskets
Cleaned throttle body
Checked that the 1990 cold start injector TSB had been performed

Many of these things needed to be done anyway, so it’s not a bad thing, but none of it made any difference to the frigid start, slow go syndrome. Having eliminated everything else, last week I swapped the ECU for an identical one in hopes of fixing this. It’s been in the single digits every morning since (minus 3 this morning) and the car has been drivable immediately. I don’t think this is a common ECU problem since no one else reported it, but if you have similar symptoms and can’t figure it out, it might be worth a try.

Thanks for all of you who made suggestions, Lucid especially.