Honda Civic EX 2002 accelerating without input.

I just recentley changed my oil and put in a new air filter in my Honda Civic. I have a little experience with changin oil but have never replace the engine air filter, although it seemed easy enough. Now, whenever I start the car thr rpms shoot up really high while in parking and the engine revs loudly while idled. Im now afraid to turn thev car for longer than a second because of how quickly the engine acceleratesm. Could any of this have to do with a botched maintenece job? Hope to hear feedback really soon and appreciate your time.