I have a '91 LX Sedan, about a year ago I changed the VSS (Odometer died, CEL came on) all seemed well for a few months. Then the AT control unit went bad and during troubleshooting I noticed that the speedometer would not return to "0" and the speed was off by as much as 9MPH. Changed the AT Control unit, fixed the shift problem elected to live with the odometer issue. Rescently I noticed that when starting the car with a cold engine the tach would jump up to appx 400 rpm, doesn't do that when warm. QUESTION is this, is there a common electrical component that could be causing this? I've been suspect of the VSS for the speedometer but I don't think the tach gets it's signal from there. Ideas?