The temp sensor is not where it should be where would it be?

Unless you buy a Clymer manual, free wiring diagrams are supplied in sections. In my search query add the name of the section you are looking for,

2008 pontiac g6 injectors wiring diagram

'cam sensor wiring' etc.

https://www.google.com/search?q=2008+pontiac+g6+wiring+diagram

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Check wiring harness to temp sensor. Conduct a voltage test on sensor using a DVOM.

It sounds like you have a wire or wire bundle pinched somewhere causing an open or a short. As you just replaced the valve cover gaskets, check very closely in all areas that you worked on for the routing and proper security of wires and bundles.
Not that it makes any difference in your issue, but didn't the Dakota go to a 3.7L V6 in 2004 (as opposed to the 'old' 3.9L)?

Sounds like a short to ground on the temp sensor circuit. What happens if you leave the sensor unplugged ? It should set a code in the engine computer.

Get an oven thermometer, run the car untill the check light goes on, using a multilayer rag slowly open the radiator cap one notch.If if the cap wiggles loose & no steam comes out , you can fully remove it. Put the thermometer into the liquid coolant , if temp is 180 F (+- 20), the problem is electrical. If steam comes out its a cooling system problem. Use commonsense in doing this. Probably the gague is faulty.

suspect bad oil pump or clogged filter

Your problem likely wouldn't create a check engine light. Sounds like you have a tempramental engine temprature sensor. http://www.autozone.com/autozone/repairinfo/componentlocations/componentLocationMain.jsp.. Look up your car, section in trouble, and information needed.

It appears to be located in thermostat housing. Two wire connector, wire colors tan and yellow.

the emission system on any car sold n the USA is tested and certificated by the EPA to not pollute for 100,000 miles, these systems include the EGR (exhaust gas recirculation) system, the fuel vapor control system, the catalytic converters, the various sensors on the engine such as lambada sensors and engine temp sensors plus many others

P0327 - Knock Sensor Circuit Low Voltage
P0332 - Knock Sensor 2 Circuit Low Input (Bank 2)

Have you had the engine worked on? this looks like maybe the spark knock sensor is either disconnected or has been overtightened in the block, to check this locate the knock sensor at the base of the cylinder block just above where the oil pan bolts to the block, it is round (with a wire connector going to it) with a large hex nut configuration to pull it out, it is in the water jacket so if you do pull it drain the cooling system and the engine block, if you replace it DO NOT OVER-TIGHTEN IT! tighten to suggested torque setting in factory service manual.