When you say "throttle harness" are you talking about the connection to the throttle body?

If not, check out this page of RealOEM:

RealOEM.com - Online BMW Parts Catalog

I occasionally have some weird thing where the engine seems to stutter. I ran across that a while back and the part was $19 so I did it. Didn't help me though.

Mine is so infrequent it has proved impossible to track down. I even purchased a BluDriver so I could log everything but even in the logs I can't spot anything fishy when it happens.