With only 57000 miles on it I would't suspect that the injectors being gummy would be an issue but it probably wouldn't hurt to use up a few tanks of fuel with some injector cleaner in it. You may want to check out your IAC valve. It could be dirty and sticky. ITs usually located close to the throttle body in the intake plenum. When you remove it use an intake cleaner that is safe for your car. An old tooth brush helps too. When you are cleaning it, make sure that the end with the spring and pintle (part that was in the plenum) is pointing down while you gently clean and dry it. You will also want to clean and dry the port that the IAC came out. Replace the valve and start your car. You could then use the cleaner to clean your plenum with the car running. You will have to put one hand on the throttle to keep the engine from stalling. Again, make sure that the cleaner you get is safe for your engine. After that, rev it a few times to get all the cleaner out. Hopefully that helps.