my 99 gts 12,000 miles has an intermittent misfire. runs great when on the gas, lots of bucking but not always when going slow. both throttle butterflies adjusted correctly. i have changed following and about to throw towel in plugs leads both coils cleaned all grounds both oxygen sensors air sensor fuel filter throttle body sensor map sensor cam sensor crank sensor pcm both cats ( 1 damaged through misfire ) could it be an injector ? is there an easy way to check which one is at fault. cheers, Brian.