If the car is idling high, I would open the hood and look for a potential vaccum leak. These can be hard to find sometimes, but I would start off looking for any ripped lines or torn lines, this is the ideal scenario and you can fix yourself relatively cheap and easily. If you can't find any lines messed with I would personally resort to cleaning things. I would throw a bottle on injector cleaner in the gas tank or take the injectors out to be cleaned. I would replace the air filter, clean out the intake hose, clean sensors on the intake, and clean the throttle body out.
FWIW - Recently I was getting a random misfire. It would show up for 5 min or so roughly every day, sometimes on start up. I spent a morning doing all of the above and after that the problem never came back.