I also have the same problem with my 94 740i. Check engine light comes on and rough idle in the morning, then after about 10 minutes of drive time its fine for the rest of the day. Curiously, the car was fine all summer (The average temp here in Palm Desert during the summer is 110-115, cooling down to about 99 by midnight). But as it got cooler when fall came, the problem started happening again. I've replaced the MAF and the "silvery" idle control valve. I also replaced the throttle body boot and checked for gasket leaks as recommended and replaced the air filter. All the plugs are new and I have individually grounded each coil. Still no help.
There is an intake air temperature sensor (The #2 O2 sensor, I believe) located on the forward passenger side of the intake manifold. Could this be the source of the problem and/or is there any way to test it? Schematics reveal that it is second in line electronically to the MAF. This is the least expensive of the 4 O2 sensors but still I'd rather not have to spend another $50 if the problem lies somewhere else.
Thanks for your help.