The four pin sensor is the temp sensor for fuel management and EZL (ign).
There are two seperate sensors inside,Unplug the connector and turn it 1/4 turn and reinstall, This will put the other sensor to the fuel manaagement.
The OVP is a good possibility as there would be no cold start valve actuation,idle-up or fuel enrichment if it were bad.
If you are not already using regular grade gasoline then switch now for cold weather.
Find out if this car has oil consumption history, If it has worn guides and seals it will be hard to start.
Mike