Honda Repair: Tach fluctuations, power battery, alternator

Question
Just bought a 89 Accord DX 5-sp manual.  The tach jumps all over the place when the car is started, stopped or coasting.  When is under power, it works fine.  The battery light is acting the same way, on when not moving and off when under power.  Battery is new and fully charged.  Any ideas?

Answer
Mike:
I would check the alternator to see if it is going out. One thing you may try is tapping on the alternator when the light is on to see if that turns the light off. As for the tach, I would check the connection to the transmission. I'm not sure if the problems are related, but I would think there are two separate problems.