Normally their factory representative would be very competent. Something strange here. Usually at least one mechanic at a dealership is up to speed as well.

Intermittent stalling might be really hard to locate though as whatever causes it has to be present only when the stalling occurs usually.

Several years ago our son in law purchased a new ford car. It would randomly stall out usually at the worse of times.

Ford spent considerable time and money on that one without locating it. Problem was solved when the car burnt because of the ignition switch problem. It had not been recalled yet for it and I suspected it may have even been the source of the intermittent stalling as well.