its TLA time!
OVP stands for Over Voltage Protection relay. It's there to protect the engine electronics from excess voltage, when jump starting apparently.
Power from the engine control unit (ECU) to the idle control valve (ICV) goes through the OVP so if its not working - they are notorious for causing problems - you lose idle control which is why your engine stalls when slowing for an intersection or whatever.
The idle control is governed by changes in current to the valve but you can check if it is working by putting a voltmeter across the terminals while the engine is running. You should see 6v, iirc, but if there's power getting to the ICV then the OVP is functioning. It may, of course, be functioning intermittently
You can also hear the valve click into open position if you stick your head under the bonnet and get someone else to switch the ignition on but not start the car. This, btw, is known as KOEO (key on, engine off)
If you have anti lock brakes, the circuit also runs through the OVP and the ABS warning light coming on is usually a good indicator of problems with the OVP.
TTFN