1999 Chrysler 300 shaking when braking and at very low spee

I have chaged my front rotors and pads for the second time it has improved. However, im still getting a little vibration when braking between 45 & 65 miles per hour. Or when slowing down between 50 to 30 miles. At high speed slowing its fine. I have changed my rear pads but not the rotors. The slow wobble feels like a bent rim but i have told that my rims are fine. What do you think is the problem and do you get many questions about this problem for this car?