check the alt bushes, worn ones will cause problems for the OVP.
Replacing the fuel accumulator to ensure a good pressure
check the Air flow potentiometer at the front . It controls the cold start and warm up RMP's The voltage at the pins can adjusted to specs after prying /removing the cover,This is a sensitive adjustment.
the wiring for the trunk light flexes near the hinges it can short but mostly opens up .
mak
300se