94 Grand am running rough

Hi, I have a 1994 Grand Am, 3.1, V6, 223,000 miles. The car has always ran great for me, until recently, when it started to idle rough especially when I start it up. It seems to sort of bog down for a little bit while I am driving, and gradually it seems to get better. I was wondering if this could be anything with my injectors, or if I am way off base. I did a tune up on it about 8 or 9 months ago including new sparks, wires, fuel filter, and an oxygen sensor. I also was wondering if a clogged catalytic converter could contribute to this, because I can hear the insides rattling around inside the converter when I am parked near a building. Also, a separate issue I am having is that when I get up to higher speeds, I can hear a whirring sound. Thats the best description i can think of. The noise seems to increase as my speed does, and it isn't continuos. It does seem to follow a pattern though. I can hear it for a few seconds and then it stops for one or two seconds. Then it does it again and stops and again and stops. I was wondering if this could be wheel bearings or if it could be soft motor mounts. Any help would be greatly appreciated guys. THANKS!!!