Stalling at Idle w/ No Load

Well, for the last few weeks, my alternator has been whining like a supercharger. I have no idea why, I am not running anything electrical that is different than it has been since I got the 4runner. When I use remote start, generally the first try the 4runner will not start. It will shut down and automatically restart fuel pump etc., and fire up the second crank. It will run for about 20 seconds, and die. It fires up again and dies a total of 4 more times before it gives up. It's been doing that the last 2 days, I don't know what the hell that's all about. It happens with everything on, and with everything off, doesn't matter.

During a huge snowstorm a few weeks back, we had a call for a car vs. pole, so I hopped in the fire truck, only to see my 4runner's running lights going, which I know I had shut off, which meant it was running without the keys, and without me hitting the remote start. I came back after about 15 minutes, running lights were off, as was the engine. Voltage appears fine according to the gauge, but why the hell is it stalling if it doesn't have to send power to anything other than the engine?