well from talking to him as I understand it, he will be driving, and the rpms on the tach will drop and raise out of nowhere, but the car doesnt actually slow down, which leads me to believe it is something electrical with the tach. And he also said it was not something that was consistent, it was random. I told him to check the wire for the tach going onto the grey plug by the distributor and he said it was fine, anyone else have any ideas?