The leak obviously needs sorting - but have you checked Dwell and FSDO settings?
If the Dwell's set too low it may explain velocity/consistencey problem. The ideal settings for each Ego vary - but I run mine at 9ms Dwell, and FSDO of 2. LPR also effects velocity if set too low, and as Lump said flush is a good ball park setting for this. My own is set about 1/2 a turn below flush, and with everything cleaned & lubed regularly, shooting decent paint will give me 280fps +/- 2 all day.
Check your settings are close to factory spec (check manual), just in case previous owner has frigged around with it. If the guns still short on velocity and inconsistent, it could be trip to planet is on the cards.