Ok...I have a 92 gt with a tach problem. When I purchased the ca the tach stayed above 2200rpm but was accurate after that. I replaced the circuit board on the back of the tach and it worked perfectly...until now. It is doing it again. as well as going up and down when the turn signals are on and stays above 2500rpm if the lights are on. The motor is unaffected it is only the tach that is effected. All other gauges are fine.
