Why does the rpms on my 96 dodge grand caravan just keep going up when driving

Plenty of videos on YouTube...

Dodge Caravan Heater Hose Replacement
http://youtu.be/lNl3TcvncPQ

sound like fuel pump failing or clogged fuel filter.

check the distributor rotor or possible cap ,

Does the sound go away when the motor warms up? If so you are hearing the lifters rattle. This is typical of the caravan.

First I need to ask is it a 4 speed or a 3 speed transmission. If it's a 4 speed when driving down the road pull it from drive to third gear. You shpuld hear the engine speed up if it does not then that means you have on 4th gear and you will have to take it to a transmission shop. If it's a 3 speed then just count the shift points if all 3 gears are present then drive down the road and see if the van goes into tcc. When you mean the rpms are high how high are they.

I am looking for a diagram that shows were the speed sensor is located on the transmission.Of a 96 Grand Caravan.

have your idle air control solenoid cleaned out!

if you have a autozone near you they will put it on the tester for free and that way you know what is wrong and what is needed to be replace.

Check MAP sensor. If PCM gets wrong data from MAP sensor it should offset ignition timing and/or make fuel mixture too lean or too rich.

How did you know that relay is bad? What about temperature sensor? BTW, what engine do you have?