I don't think OVP failure would cause total engine shutdown. Rough running and poor starting, yes. The give away with the OVP relay is the ABS light coming on.
I think you should follow 5banger's advice and go for the fuel pump relay
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)