2003 Dodge Neon

I own a 2003 Dodge Neon with about 55,000 miles. I have been reading some of the questions asked about Neons and I noticed that it seems normal for the cars to shake, but lately when I am braking and the speed decreases to about 30 miles per hour I feel something shake for about a second and then it goes away. I don't know if this might have anything to do with the transmission. Thanks.
February 2, 2007.

Is this as it down shifts? Very well may be a tranny issue. Has the transmission filter been changed yet?