Quick update - the SES light went off when I left the office yesterday and has not come back on. However, when I started the car this morning and drove down the road, same low power/surging without an SES. So, the surging happens both in open and closed loop operation. No SES light accompanying the problem this morning.

Please offer any suggestions. I've read MAF, catalytic converter, O2 (event though new, Bosch has problems) as possible causes here on the site. Which of these seems most likely given my symptoms?