i have a vq35 stripped to down head and block, i put compressed air into the cylinders to hold the valves while i do springs and there's one valve thats leaking air into the intake manifold. it seems odd that only 1 valve is messed up so i was hoping maybe adjusting valve lash could cure the problem. any input?

 

Since your replacing the springs, you must have the cams out. That being said, lash is not affecting your valve seat seal.
Install spring, apply air, tap valve stem with soft faced hammer and recheck. Could be a bit of carbon on the valve face.