On cold mornings my 4.6 stalls on start up
 

I searched but didn't find anything about this symptom.

It's been in the 30s here the past two mornings and when I start my car, it stalls as soon as the RPMs come back down. On the second try, I just have to give it a little gas and it stays running. It's fine the rest of the day.

Fuel pump? throttle body?

Any ideas?

Try disconneting the MAF and see if it does the same thing. If it starts acting normal, then you need to replace the MAF. You can get away with replacing the sensor vs the entire tube, just search around on eBay for a bolt-in replacement.

mine did that once. hasn't happened again. It does dip a bit before settling into an idle after start-up. More than on my 740i anyway. I'm not saying it is "normal" here, just commenting that maybe the 4.6is could be a bit more temperamental than a 4.4i especially on extreme ends of things - given the tuning was done by Alpina for performance, not by BMW for 100% reliable and fool-proof operation under every condition.

That said, mine has always started up just fine even when up in the Sierras and morning temps are typically in the teens or low twenties.

How many miles?

MAF or IAC.