1998 Volvo S70 • 5 cylinder 2WD Automatic • 250 miles

What will cuse the Iac on a 98 volvo s70 to iddle high n low constantly? As if some was given the car gas? Althogh no one is, I put a new one on the car and I'm having the same problem. So put the old one back on. What causes the IAC to react in that way? How can I fix it?
August 23, 2011.

The IAC is designed to regulate air to the intake at an idle. If it is good and you are still having trouble, make sure you are getting proper voltage to the IAC and also check for vacuum leaks.