I have a 2002 dodge stratus with a 2.4 liter 4 cylinder. I just had to replace

What is your question?

The timing belt. Now before we took the old belt off the book told us to set the timing marks on the two cam gears to point towards eachother before we removed old belt so we did that and replaced the belt and put it all back together. The car runs great, accelerates good and rpms come down good. I noticed now while you sit parked for a minute or two whether your in gear or not the idle runs lower then normal. The car usually runs around 900 rpms at idle and now it's about 700 rpms. Why would it do that