Hi there,
I received the ECU from France and installed and test ridden. Indeed... it didn't fix the issue. GSAddict, it looks like my next swing will be at the TPS, thanks for that direction.
I've looked up the part number (1363-1721-456) stamped on my unit and it seems that that part number is the same part as used in several series of BMW cars. They are available from various sources, starting at $17 U.S. (spooky!) One site lists theirs as O.E.M. (though I'm not sure how to confirm that,) made in Germany and sells for less than $40. It certainly looks like the correct part and the tech I chatted with stressed that it was indeed OEM and from Deutschland... I'll report back on the part and whether or not this latest gamble has solved this ongoing conundrum.
Thanks!
-l-