[firebird1324]

hmm...sounds like you have a pretty good sized parasitic drain. you said it happens at different time intervals too, so that means you've got an intermittent problem. one of the only ways you really have to check it by yourself is either a.) sit and wait after you shut the car off for however long it takes your modules to fall asleep and see if anything noticable stays on, or, turn your car off, get yourself a voltmeter, put it on amps, put it in series with your battery positive cable, let it sit for about half an hour, and see if you've got anything drawing amps. if you do, it's time to start pulling fuses and doing the same amp check, if you have a draw larger than a few tenths of an amp in any given circuit, you've found your problem. on the rendevous, you should have a fuse box under the hood, under the drivers side dash (i think) and one attatched to your bcm (body control module) and that is located in the center stack of your passenger side.

or, take it to a GM dealer, and they can do the same check in alot less time. (there is a special tool that elminates the half hour waiting time, and the need to disconnect your battery.)