I concur about the OVP being the source of warm start problems. The first thread I ever posted involved a warm start problem, and replacing the OVP solved it.

The rough idle problem can be caused by a number of things, electrical, vacuum, or fuel system. That will require a bit of top-down stepping through each of the systems to rule out causes, otherwise you end up just "throwing parts" at the problem.

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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