any had a promblem with a msd box 6al. that when i hook it it up.it ran fine and the rpms where at 1000 and when i hit the gas the tach does to zero and then back to a 1000 rpms. now other people i know didnt have a tach adapter same year car why is this and why do i need a tach adapter form my car but other 86 owners didnt have one.