Before buying another wall wart, try this:
The 996P2 comes with a wall wart, but it also comes with the cables needed to work in your vehicle. Use the 12vdc cable to power the scanner in your vehicle. If it works with no cutting in & out, then as earlier suggested, the wall wart is bad. Since you just received the scanner, contact Bearcat Warehouse & ask them either for either a replacement wall wart, or exchange the scanner for one that works correctly. If, even when powering with 12 volts, the scanner is still erratic, then it needs to be exchanged.