Question

The P0340 codes only when the engine reach idle.. but no rough idle or anything.. do have a lack of power at higher rpm.. but when i erase it everything work fine.. until i get dowb to idle rpm again..

Answer 1

The camshaft sensor generate the signal , as long as the power to is good (B+) and it ground is good a good functioning  camshaft sensor will produce a sufficient signal, component do wear out in time, just like shoes and tire, may just be time for a new sensor.