My RPM guage is all wack. It has me idleing at between 3 to 4 grand and when I am in motion it goes past 7 and sticks to the furtheset point it can reach. Somtimes when I turn the car off it goes up to seven instead of back down to 0. Does anyone have any idea on a solution for this or should I jsut buy an aftermarket mechanical gauge and if so, how hard would that be too hook up?