Did you ever resolve this problem?

My recently purchased 300E runs excellent with one exception. It sometimes stalls right after starting or stumbles for few seconds until idle stabilizes.

I checked the duty cycle from X11 connector and here are the results:

Ignition On, Engine Off: 50%
Engine at Idle: 48%-54%
Engine at 2,500RPM: 68%-72%

What would cause it to be 50% and not 70% with engine not running?