Thanks to everyone for the replies. I'll try to address as many responses as possible.
My boat is a 1985 Catalina 22. The main does have battens. Now, CURRENTLY one of my battens (2nd from the head) is missing. However, I was having this problem before this batten got lost. How that happened I have no idea. A few weeks ago I took the boat out in some pretty rough winds, and I actually had one of my battens fly out and almost hit me on the head in the cockpit. I replaced it, but I suppose it could have fallen out again in rough winds when I wasn't paying attention and is forever lost. So the fluttering is significantly worse now, but it was still a problem when all the battens were in place.
Now, for the outhaul, cunningham, and traveler. I just noticed today that the sail looked a little slack along the foot, and I was able to pull the clew back quite a few inches with the outhaul. However, this was to no avail to help the fluttering. I do not have a cunningham set up. I do use a traveler, but I usually keep it locked pretty much dead in the center. I would love to post a pic, but I don't have those privileges yet (I don't have my 10 posts).
Again, having sailed in only 2 boats in my lifetime, and one of those boats being my own, it's hard to say how baggy my sail is. It does LOOK baggy to me though. As mentioned above, even with the outhaul fully tensioned, the sail fully raised, and the vang tensioned, the bottom 10-12 inches or so of the foot looks kinda like a deflated plastic bag. It's like I can't apply enough force anywhere to make that part taut.
It doesn't look like I have a leech
line. The only
lines anywhere near the clew are the outhaul and reefing
line. Maybe I can do some searching around for a DIY leech
line as was suggested.
There are several members of a local sailing club whom I have met, so if I run into them I might get their input as well.