Hi Mate,
I've had the hunting issue every year I take the car out the garage from the winter (battery disconnected). I got help from a friend to take everything apart and replace wiring and clean iacv etc...I then found the service manual... In my case it's solved by doing the ECU learning...
alright,
I had this problem after laying up the car for a year and a half... went through everything cleaning IAC valve + new gasket, new wiring (as the black wire at the valve was loose), checked over for vacuums etc and this is what fixed it (would advise to try first)....
ECM/PCM Learning...