Two things concern me here, the first is, What scantool are you using? as P0340 is in fact Cam sensor not Crenk sensor. Secondly are you saying the map sensor reading is 50Kpa? If so this is too high, it should read around 35 at tickover. Check with a vac gauge to see if vac is low. This is sounding like a cam timing problem as Tom says. Your landrover man is talking out of his hat as I seem to spend my life resetting cam timing that other people have managed to get at least 1 tooth out and yes these are usauly runners.