My idle is pretty smooth until I turn an accessory on like the defog or a/c. Then it surges up and down while at idle. Is there anyway to fix this? I was just thinking about this, this morning while sitting in traffic as I found it kind of annoying.

 

The VE table in the Prom needs work in the cell the engine is running in perhaps. When I turn the A/C on with my cammed 305, the vacuum drops by about 10 KPA which puts it into a different cell.

Another thing could be a ground issue.

 

Thats probably your a/c clutch clicking on and off....its really no big issue if thats the case. When you start it up in the morning let the car warm up for about 3-5 minutes before you take off, and the idle should set steadily....its no big issue and completely normal if it is the a/c clutch.

 

If your A/C isn't perfect, then my car used to do that when it was low on Freon. When I got it recharged, it never did it again.

 

that's nice to know it's probably the a/c on mine to i'm guessing as i have the same issue with it as you do it sounds.