My sons saxo was playing up two weeks ago. It was reving high. It was plugged in and no fault found. Since then, all sensors removed, contacts cleaned and then put back on. Now it will not idle and stalls. If i hold the throttle on slightly, it will run but the revs go up and down, they will not be stable. I have thought of everything so now was wondering if a sensor is playing up or not. Any one have any ideas.