1994 Dodge G Caravan speedometer broke

I have a 94 dodge grand caravan. 3.3 engine, Auto, no abs. A couple months ago while driving the speedometer and the rest of the gauges fell to zero and the car felt like the transmission went to 1st gear, a few seconds later the gauges went back up and the car went back to driving normally. Now the speedometer doesnt move, and the car doesnt seem to shift gears untill the check engine light comes on and the the acr seems to get more power. not the same as before, but a little bit better, but the speedometer still doesnt work. What could be the problem? is it the Throttle Position sensor? is it the speed sensor? if that, where is the speed sensor on a 94 caravan? please help....runaround