Ameya, tunning with the nose up is the best way. However when you are tuning your throttle is wide open. Your problem is not long verticle lines, it is hovering when your throttle is only part way open. One last thing to try. If you are holding a constant throtle setting when hovering, try pumping it a little bit. You know work the throttle back and forth. This may increase your tank pressure enough to help with the problem. If not I suggest again the Cline Reg.

David