Help With Mytouch 4g? (not Slide)?

I am new to the android market. I got the mytouch 4g about two months ago, and i absolutely love it. However, its beginning to act like a 10 year old computer than doesn’t want to run anymore. I don’t have a problem with battery life because I have a car charger. I downloaded AVG anti virus, pop ups kept popping up saying “your phone is too slow” so I would download whatever it is. I have 2 task killers, android assistant and android booster. AVG also offers task killers. I am constantly killing apps because I thought I was helping with my battery, but lately I’ve heard thats bad for your phone. My phone also when I hold it up straight it turns to the side, I’ve calibrated it and nothing. My navigation is twenty yards behind me and I’m missing all my turns, then it freezes. And the worst is the camera is amazing, it takes the best pictures but when I went to have them developed the resolutions were so low they couldn’t be developed. The resolution is set on the highest 2592 X 1496, yet the pics were saying 180 x 360 or something. And not only that when I inserted my SD card into the slot 1,576 pics popped up. I didn’t take that many. Not only the ones I had deleted were still there but pictures of websites I had visited, and a bunch of weird things. I dont have an unusual amout of apps, about 80. But I transferred music from my computer to my phone and some of it was from limewire. Could that be it?? A virus? I have anti virus on both my comp and phone. Can anyone help me please?