Check engine light comes on and gas gauge goes from it current position to empty going down the road

Remove the gauge cluster and check for a bad ground. If it is bad you can resolder the trace on the back of the cluster back to the groung pin for the connector.

sounds like you may have a bad fuel level sender problem. as for the check engine light coming on and storing a fault code that is a separate issue.

Computer glich.

Reset vehicla puta by removing battery terminal for a min, this should reset the computer, give it a few mins to re-set before starting brrmm brmm!

faulty feul sending unit or bad ground will need to use a meter to test the system

There is a small float in your gas tank something like the one in your toilet tank(no I'm not kidding).Its position regulates an electrical current and based on its resistance gives a reading on your gas gauge. My best guess is this float got a bit stuck in the low position and it shock free after some time on the road.This is more common than you would think.Keep an eye on it and if it freezes in empty position or sometimes full position it will need to be replaced. Hope this helps,good luck.

very well sounds like the sending unit in the tank. Try running some octane booster and fuel injection cleaner in tank of the truck to loosen any deposits on the float.

This is a safety feature that the vehicle brings. You need to reset the E.C.U on dealership or it will keep doing it to you. It was probably caused by one single time that you did not closed the fuel cap correctly. Good luck

Sounds like a bad sending unit or a bad gauge. All 2000 an later GM vehicles seem to have problems with their gauge clusters. Hope this helps.

You will have to get the error code before the engine light goes back off. You can do this by inserting the key into the ignition, then turning the key key to the on position three times with in 5 seconds. Remember this is the on position no the start position. Once you have done this the odometer will show the error codes briefly. They will look like this "P0202, P1225, P1400. Make sure you write them down because they can go pretty quickly. Once you have the codes go to the link listed below. It will give you a brief description of what the codes mean. If you need any thing else just let me know and I'll try to help.
The first link will have jeep specific codes, the second will be codes generic to all manufacturers. Just scroll down until you see the code listings.
Good luck.

http://www.obd-codes.com/trouble_codes/dodge/

http://www.obd-codes.com/trouble_codes/

i know that if the gas cap is loose then the check engine light will come on. as far as the fuel gauge going up and down the "float" you have in your tank could be getting stuck. This is a pain in the rear to change because you will have to drop the fuel tank and either replace the part connected (best bet) to it or make sure the passage is clear.