You need at least 125 psi to lift the front and you need a good amount of volume. You therefore need an air compressor that has a large tank and can put out that pressure. If the front springs are really shot, there is no saving them. If they have small leaks, then the front should raise. It sounds like you have really bad front springs, or, more likely, a shot compressor. I say this because you only need 80 psi to lift the rear. If you have a weak compressor, the rear will level, but not the front. Replace the compressor and see if the front lifts. If it does, you might be able to use some Tire Slime injected with a thin straw to the bottom of the air spring to temporarily seal it until you can replace it. Honestly though, if you go to the trouble of doing this, you are one clip away from replacing the thing. Springs take about an hour per side for first timers and can be done in the driveway with hand tools. Remember to lube the O rings with silicone and do not get Slime on anything else.