It's noisy when the engine is revved, worse if the car has been at idle, better if the car has been driven on the interstate. Usually improves some as the car warms up. So I replaced all 16 lifters. The same valve(lifter) is still making noise. Is there anything besides the lifter itself that would cause a lifter to not pump up or operate properly??? Valve, spring, rocker arm, and rod are okay.