I've noticed the pass few months that when i'm at a stop and holding the brakes the car will shake and the head lights will dim, it also shakes when the radiator fan kicks on. But if I put it park and let off the brake pedal it'll stops but it will still shake when the radiator fan kicks on. So it only does it during electrical draws. I have three guesses either the battery, or alternator needs replaced, the engine needs to be grounded better, or the idle is set too low. My question is can I even adjust the idle or is it electroniclly set like the ford rangers are, do they make an aftermarket ground wire kit for the SPI. or should I just look onto the obvious and replace either the battery or the alternator. What do you think??