hey guys, my tach is getting jumpy at over 2500-3000 rpm. when the car is cold it seems to be ok but the as it warms up it starts messing up. as i accelerate it starts out smooth but then once it gets higher rpm it will start jumping up like pauses for a quick second then jumps to the motor speed, then does it again. it also will do this as i decelerate. it seems to be ok at low rpm and climbs/falls smoothly when cold. where do our cars get the signal from? i do have a new coil pack installed in case its built into the pack.