Sometimes the RPMs will start to fluctuate while the transmission is in park, then the car will start to shake and eventually shut off?

Sometimes the RPMs will start to fluctuate while in park, then the car will start to shake and eventually shut off. If the gas is pressed while this is happening the RPMs do not change other than the odd fluctuation. After that sometimes it will have trouble turning over and other times it will start back up as normal and allow you to drive as normal. The check engine light only came on tonight and this has been happening intermittently over maybe 2 months, although the car is not driven a lot, it is driven daily for short commutes.