Well two things that could cause this issue are the mass air flow sensor and a vacuum leak. the one you can check for is the vacuum leak. you will have to remove the engines cover to view the vacuum lines and you will have to check for broken or cracked line visually and if you don't find any you can go one step farther and use a brake cleaner spray or starting fluid around the intake and vacuum lines to see if the idle changes or smoothes out. if so then you can concentrate the spray in the suspected area to confirm it. if not you should bring it in to be looked at because with out the correct tools and computers you will waste alot of money and time testing a mass air flow sensor.

let me know if you have any more question. good luck