You are going to have to remove the whole inside door panel to get at the solenoid for the powerlocks. (Relax, It's a piece of cake) Just remove the little armrest and remove the screws that hold on the black handle/lock panel, and then you should be able to wiggle the inside door panel a bit and get it off. (I think you need to pull it up or something)
Once you have it off, in the middle of your door you will see the solenoid for the power door locks. Lubricate this puppy real good with some WD-40 or Silicone Spray lubricant or something. (Make sure you get inside the rubber boot) Also, be sure to lubricate the striker area. (Just follow the metal rod that goes from the lock slider to where it goes in the rear of the door. This is what was sticking on mine)
If it looks like it moves, it probably wont hurt to make sure it is well lubricated. Then just work everything back and forth until everything is operating smoothly, and put the door panel back on. (reverse the removal procedure)
From: Dan Schooler