Check for vacuum leaks, make sure all hoses are connected to something. Clean out your IACV, its on your Throttle Body. if that doesn't work, check if your EGR is stuck open. If you have no idea what i just said, get a "Chilton's" manual for your engine/car...those are great for beginners and experts alike. And if all thats good, check the MAFS, sounds similar to problems when they're unplugged.