I have a 96 Dakota, 4 cyl that idles high and is using extra gas. Cleaned the throt body. My temp gauge is also bad, using external temp sensor (computer cannot monitor the temp of the engine). Could that be one of my issues? The sensor in question is broke off. At 232,000 mile, going for 1/4 mill.... A lot of little things wrong, like speedometer jumping all over the place, guess speed sensor.

That broken sensor is most likely your problem. If the PCM "thinks" the engine is cold, it will run rich and kick the idle up a bit.

Tom, thanks for the reply. I think I mixed too much information in, I still would like to know what sensor, if it is a sensor, is at the back of the valve cover. It has one wire. My temp gauge stopped working in the dash, hence the external temp sensor (non-computer connected). I really need this truck for work, but I worry it is limping to it's death. Any help would be appreciated.

Yes the coolant temp sensor could be causing your problems. I'm not 100% if that is the coolant temp sensor. We have the 96 Dakota Factory Service Manual to download in the FAQ in this section. That will tell you everything you need to know.

If it is the one wire connector (like you said), then it is just the temperature sending unit. All that does is control your temp gauge on the dash.

The coolant temp sensor (2 wire connector, on the drivers side of the thermostat housing) is the one that sends a signal to the computer and can cause it to run bad.