I think you are right about checking the FCD. I got a wifi OBDII logger for my android phone and it shows that the transition back to closed loop occurs when manifold pressure goes into higher vacuum. I'm still not sure if an increase in mani pressure is what causes the initial transition to open loop. I always thought that too high of voltage in the MAP caused fuel cut. My 99 seems to get fuel dump instead!

Now I gotta find my instructions for the symtech FCD...

EDIT: Played around with the little dial on the FCD today (really difficult to dial in, I need to drill out the hole on it more b/c sometimes I can't tell if the screw is even turning). It appears I an make the rich condition occur more frequently, but can't eliminate it entirely. blah

2gnt: '99 RS-T, killed by a toyota, pending rebuild...
Daily: Volt
Daily #2: '99 EVG ebike- STOLEN by PEDRO