engine idle flucting
 

Yesterday I pulled into my parking space and noticed that my idle was going up and down, would go up to about 1,200k, and drop to about 900. Havent drivin it since yesterday afternoon when I noticed it. I was trying to stop the "idle stubble" in the summer and made it idle at about 1k. Coulnt fix the stuble. How I drive I dont downshift all the time coming to a stop in light trafic or a stop sign. When I would pop it out of gear the RPMs would drop to about 800 and then go back to idle at around 1K. Still does this. What could be that problems for this? im thinking a vacume leak somewhere that has gotten worse, maybee?