Electrical stupidy issues

[MaxPlusTen]

well maybe you guys can help me out here... cars been running fine until just recently. I kicked on my a/c for the first time this year and it knocked my voltage down to about 11-12 volts and boged the whole car and gave it a miss at idle.... about a week before the car threw a P0300 Random Multiple Cylinder Missfire (dunno if thats related or just a stupid quenceadence) but at any rate i cleared it and it went away with no return... Now everytime i turn on the a/c though the voltage drags down and it will miss... i have 3 ideas... first and obvious, i think my altenator may be about to take a dump (i also had a battery crap out about a month before this). Second someone told me theres a sensor that has something to do with rather the compressor increases the alternator output while the a/c is on. and my third and most feared is my opti is gonna take a dump on me here soon... anyone that can help would be greatly appriecieated

[LS1_TA_2002]

Your A/C compressor could be starting to seize also. This can slow the motor down slightly at idle.

[MaxPlusTen]

i should note the a/c is working just fine... blowing cold... just affects the idle so i doubt its the compressor itself...