Demon Possessed BCM...
 

Hey, I wanted to let you know that I have the same recipe for insanity with my l200 and it is all caused by the least obvious culprit possible. Does your car have the traction control system? If so, do you have a switch to turn it off? ....this has worked for me for several months, ( I'm on side of the road now) perhaps you could try that.... Its the ETBCM on my car that's bad....for some ungodly reason, Saturn chose to incorporate the traction control into the body control module....the end result appears to be a demon possessed car that requires an $800 exorcism.... And I've read online (unconfirmed still) that until the 2003 model was made....this was a part that had to be bought new due to not being flashable.....
mine is a 2002 of course

Anyways....hopefully this helps you....
Best of luck!!!!