How can I share one power supply between an arduino and servos?
You need to figure out your total current requirements. Don't guess, figure it out. What is the peak current draw of the servos? of the other components? Add everything up. If the total is within 20% of your power supply current, that may be the problem.
Also, servos tend to draw spikes of current. You might need to add a filter capacitor to the +5V rail on the Arduino to even out dips as the servos cause sags in current before the voltage regulator in your power supply can compensate. (Put the cap between +5V and ground right at the Arduino.)