You can also force it to re-learn its idle strategy by disconnecting the battery for a few minutes, reconnect it, start engine, don't touch the gas, idle at least 5 minutes in Park, idle 5 more in Park with AC on, 5 more in Drive, and 5 more in Drive with AC on.
Only two 5 minute cycles needed with a manual transmission, both in Neutral, second one with AC on.
Could also be an IAC sticking (or bad). You can remove it and clean its innards with that Seafoam.
But it really does seem awfully coincidental that you messed with your air filter and NOW you have a new problem......I'm going with Bob. Intake tube leak or contaminated MAF if the new filter is oiled. But you can try the idle relearn stategy for kicks. Might help.