ok i have an 85 that i bought a few weeks ago and it has a problem when running i get these knocks while drving something i have read a lot of ppl are strugling with, my entire cooling system is new i have a new o2 senser and im running a low grade gas right now also i just had a hugle fuel leak in a line relpaced so could air be in the lines? and the knock came before the leak but it got wores after and the ideal got worse too. before i start buying parts were should i start last night the knock got really bad and the gas milliage gauge was acting up when a knock would happen so i think that could be bad gas o ( juat fueled up) or air in the lines from the fuel leak. should i change my fuel filter i know it good to do but can it get cloged were should i start with this