Also, are you suing a breadboard to connect this project together? Did you make the jumper wires yourself or did you get a bundle of premade wires? 22awg wire will allow 7 amps (American Wire Gauge Chart and AWG Electrical Current Load Limits table with ampacities, wire sizes, skin depth frequencies and wire breaking strength). If you are using a breadboard and your 22awg wires are plugged into the same row, that breadboard can give, what, 300mA per row; someone correct me on this. As can be seen the math to supply several servos from a breadboard quickly shows a losing trend.
Next, those wires that came in a kit or bundle, the ones you did not make up yourself, are most likely, AL and not copper. The 7amp rating drops down, and those premade connector pins don't mate well with the breadboard. Also, if you bought the discount breadboard, drop that current rating. A lot of intermittent issues go away when you use wires connectors you made yourself with good copper clad wire, for the servos.
Hopefully, you got lots of areas to take a look at now.