On your 98 Pontiac Firebird why do your brights dimly come on with your regular lights and turning on your brights kills your engine?

You have a low level short somewhere in you headlight circuit. Probably somewhere under the hood. Trace the wires carefully starting at you headlights and work back to the firewall. Anything suspicious should be looked at carefully NO BARE WIRES ANYWHERE TOUCHING ANYTHING! It's redirecting your 12Volts to ground and your engine will not run without it.