Did you take it to the Apple store to have them look at it?
It sounds like your internal clock battery has either run out because it is not being sufficiently charged or fried due to the soda spill. Your computer's startup troubles are most likely due to the power manager being corrupt, which happens with a weak internal battery. Try removing the main battery and the power connector - check to see if the Sleep light on the front of the computer blinks. It shouldn't....If it does, the internal battery of your Powerbook has gotten weak. I'm assuming you've already tried charging the powerbook, so a technician will most likely have to replace the internal battery if it won't charge.
If you haven't yet, you should take the keyboard off your powerbook and see what damage the soda spill did. Instructions are at
http://www.macfixit.com/article.php?...41012075239848