It's about a 95% probability that it is caused by a dirty throttle body.
Buy yourself a $2.50 can of throttle body cleaner at AutoZone or some such store, remove the MAF, and have at it.
Follow the directions on the can of cleaner - use the whole can.
Reattach the MAF and all the wires and nonesuch, and you'll be good to go.
If you have any other questions, you may want to message BigJim here on CEG. He is the king of all that is throttle body-related.
