I am glad you were able to get it working! Thank you for letting us know and sharing your file for others.
Overheating is typically a sign that the servo is underpowered for the application. It sounds like you are already using some pretty strong servos, although this listing from the manufacturer of the MG995 is showing a stall torque of 11 kg-cm. Unfortunately, I cannot make any specific recommendations without knowing your required specifications. If you know the torque requirement, I recommend looking for a servo that has a stall torque of at least 4 to 5 times your requirement (i.e. keep the normal operation at around 20-25% of the stall torque).
From our selection, the FEETECH High-Torque Servo FS5115M we carry has a stall torque of 15.5 kg-cm at 6V, but that might not be enough (especially if your servos are actually 15 kg-cm). The next step up that we carry still in a standard size form factor is the FEETECH High-Torque, High-Voltage Digital Servo FT5121M, which is a 7.4V servo that has a 20.5 kg-cm stall torque at that voltage.
Brandon