A couple weeks ago I had a Code 16. Changed Opti, Spark Plugs and wires. The code went away. Now the problem I'm having is when sitting at idle the engine is skipping a lot and the voltage drops especially when you are running the A/C. When you are driving the car runs fine. Any suggestions on what to check? Thanks!!

 

Idle control valve?

 

The low voltage you referred to, is that measured at the battery? If so, it should be approx. 14-15 VDC (engine at idle, no A/C). If its much lower, it may be the alternator. Are you using under-drive pulleys? That would account for the lower than normal charging voltage.