While it's not a common solution, if you have access to a different power source (such as a portable power supply), you might try connecting the stereo to that to see if the boot loop persists. This can help rule out potential issues with the car's electrical system.
To adequately produce the sound that a 3000 watt amp is capable of producing, at least 1/0 gauge power cables, 16 gauge main speaker wires, and 12 gauge subwoofer wires are required.
A 1000-watt amp should be powered by a 4-gauge size. But the best cable to use is frequently determined by a number of variables, such as the class of the amplifier and the required length of the connection.