Before you go mucking about with the adjustments on the 3-n-1, make sure that your heli is mechanically sound. Crashing a heli several times will knock something out of whack even if you just replace all the obviously broken bits.

Are you servos working perfectly? (no skipping or erratic movement)
Are you links all straight?
Is the tail rotor on straight?
Is the mainshaft straight?
Are your mainblades balanced?

These are some things that will make the heli fly oddly.