does anyone know what will make my tach bounce when cold (engine) and read correct when later warmed up....also it used to rev well even cold but now the motor must warm for at least 30 seconds before i can smoothly rev it up. no new tune ups or anything just kinda started doing this but funny it straightens out after warm tried another module i had but that one is questionable. i have a gm one in it now. runs good no miss.Ive read new cap maybe new module but its fine once warmed up....................thanks