i have a 94 Mercedes Benz, and i thought at first i might have bought bad gas and it could still b it but iv put a new fuel filter on it. before the filter it would act like it wasn't getting enough gas during take off. it would kinda shake then smooth out. it will idle fine. it stopped for bout a week after the filter and then just the other day it did it to me twice but since then. i have already put all together about 5 bottles of gas treatment. as soon as i put that in there it will, stop every time and as long as i keep it between 1/2 and 1/4 of tank it will run fine? please can someone help me out with this?