help

i have a 2001 extended cab s-10, running 4 1/2" valves. the problem is...

i air my tank up to about 160 or so, then when i try to lift the front up, only the right side wants to come up. eventually after f**king with it for a while, the left comes up. all of my valves are mounted in the rear, but that shouldnt cause that should it? my lines in the front are the same length and they are not pinched or anything...someone please help me out this annoys the piss out of me and i have to go through it everytime i air my truck up.

thanks