if the front bags wont raise, then i cant see how your back bags are filling up, because the way the air ride works in these cars, if the front tries to raise and wont, then the cycle stops and wont let the rear fill up. there is only one compressor, if sounds like your front struts have such a huge leak, that the air is getting out faster then the compressor can fill them up. that spring kit is around 400 bucks. to replace your air ride, front struts are like 260 each, that right there is already more then a spring conversion.