Here's my problem... I'll just be driving down the road and it will feel like I slam on my brakes, my car willl not actually come to a stop at all but it will feel like it does. Any thoughts on this?

Is it auto or manual. If it is auto...is this the only when it shifts? I'm having a little difficulty understanding exactly what you mean. For instance, is it like a lag between shifts..maybe even accompanied by a jerk, or is it literally slowing you down significantly according to your speedo? More specifics would help us help you.

Also do you have any Check Engine lights, or lite up/blinking lights near your shifter?