Mitsubishi

I have a p reg mitsubishi space wagon, 2 litre petrol auto. A couple of weeks ago once warmed up it started ticking over at just over 2000 revs. I found if I unplugged the wire to the air flow meter the tick over would imediately return to normal tick over. Just under 1000 revs but when plugged back in revs jump back up. In my ignorance I figured this to be the problem and send air flow meter away for testing and referb which has been done. Have received it back and refitted only to find problem is exactly the same. Where else should I be looking to rectify the problem? Have also given throttle bodies a good clean out with no effect?