Shifter feels like I can pop it out....
 

by pulling up hard enough. The shifter is very loose. You can wiggle it around WHILE it's in gear. What is causing this?

The inner boot as it's called. Go to mazdatrix and you'll see what I mean. It's the metal plate that the shifter bolts down with(has a rubber boot on it). If you take your top shifter boot off (should just pop up) and take the 3 rubber boots out as well, you should see it. Check for tears/excessive play around there. Mine is this way and the ball buldges right out. Nothing $25 can't fix!