As i was slowing down at a light today, at about 5 mph, the front end started to shake horribly. The rpms were jumping under 1000 constantly and when i let off the brake it would jerk forward. Then when i accelarated it was fine. Did it about 3-4 times day. Any ideas?

Something's broke.

Is the Check Engine light on?

I'm assuming it's an Automatic. Any more information would be greatly needed (i.e. went through mud puddle yesterday, jerks today, etc.).