Tranny problems with 95 dodge avenger

Would anyone have an idea where the computer for my transmission would be at? Or where I could find a diagram for my transmission on line? I have had my little car for almost two years. She runs great, but sometimes I will be driving down the road and she will red line. I loose third/overdrive. When I step on the brakes she kicks down hard. I can pull over, put in park and turn off the car. Wait about three to four seconds and I have no more problems, sometimes. There has been a time or two when I would have to do this like twice in a row before it stops. Then it won't happen for weeks, then all of a sudden it happens again. Someone told me that it might be electrical, or the computer. Any idea out there to help me out?
Thanks Kim

Go to http://www.alldata.com/ they have good online manuals. Cost $25.00 per year for the first car less for the second. Ask if they cover transmission before you buy.