I have had this problem for over a year now, and I also have heard that the transmission "Reverse" and "Drive" switch (or sensor) can send bad codes and cause this effect...I will one day research this and find the absolute source of the problem.

In the meantime, I had replaced the OVP some time ago to cure a hot start problem, but the surging still exists...so rule out the OVP

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car