I installed a Price-Fister lavatory faucet with 1/2″ to 3/8″ tubing and the pressure was too low. I got sick of it and bought a new faucet with 1/2″ to 1/2″ tubing and at first there was noticable increase in pressure. But then the new faucet flow dropped to a dribble. I checked the valve openings were wide open, the screen was clear, etc. I don’t get how the pressure can be so low. Is there a chance there’s a leak in both the hot & cold supply lines in the wall that cannot be heard? I’m ready to tear into the wall to see. HELP!