alternator help

[BLue STeeL]

alright, for starters its the stock alternator out of a K8. i just installed my indiglo gauges and wired them to the dash dimmer. ever since my car has been getting low rpms at complete stops and sometimes stalling. i havent had any problem with the car until i put in the gauges. I should also mention i'm running a 4 channel amp to power the 4 speakers, and a 2 channel powering 2 12" subs. is there too much strain on the alternator? or is there any other reason my car is getting these low rpms sometimes? i'm thinking of trying to swap in a millenia alternator for more power. any input is appreciated.