Ford Repair: Gas gage, air control valve, fuel guage

Question
I have a 1996, 3.0 Ford Ranger.  The gas gage works when it wants.  Can I repair this thing easly?  Next question is my check engine light is on and I tried to locate the problem using Auto Zone free diagonstic computer.  It seems that enough information is not given.  The engins at times idle real fast and hard and I have turn the vehicle off and restart it until it stops.

Answer
As far as the fuel guage, I would suspect the sender in the tank, but not replace without testing first. You can access the fuel pump module one of two ways, either drop the fuel tank out of the frame, or lift the truck bed for easy access. Once you have the fuel pump module out, check the sender for resistance. At empty the reading should be 22 ohms (approximate) and full 160 ohms. Sweep the float arm slowly and see if the ohm reading drops out at any point.

As far as the CEL being on, there should be codes to retrieve. If this is a 4X4 there might be codes in the GEM module relating to the transfer case. One of the common things for the idle sticking is the idle air control valve. I don't recommend replacing anything until you find out why the CEL is on.