Low Idle, after replacing Idle Air Control Valve

Just went through a major repair, timing belt and water pump replacement. 3 days later the engine began idling very high (3000 rpm). I was told the IAC was getting stuck, they tapped on the trottle and it fixed. So I replaced the IAC myself and now it idles very low, less than 800 rpms, it actually bounces from 500 to 800 rpms. And when the ac compressor kicks on, the car feels like it wants to turn off.