i got an 02 gt with a sct tune on it. i have it set for 87 and only added 1 thing of fuel to even out my cai. the car runs good but when under load or if i go wot i get a rattle/knock sound. it does not do it at idle(only if i hit the trottle. the car was sitting for like 3 weeks and i went to get gas i put 87 from da same mobil i always use and it started doing it. also i dont know if there related but the car has been dieing out after i start it but it always starts back up