I have a 6-cylinder that seems to stay ice cold on one half while the other half warms up when ran, and while this is an issue, the gauges are reading the engine is overheating yet physically gauging the temperature like feeling the air coming off the engine, or touching the alternator, the engine, and the radiator cap all are either cool or slightly warm. So far, replaced the alternator, battery, and starter.

So what gives? Truck also smells like gas sometimes and is burning fuel faster

 

The alternator, battery and starter wouldn't cause the overheat problems. What thermostat are you using? If you aren't running one, that may be your problem. How old is the water pump? If you have a computer, it's in open loop mode and is dumping fuel; to try and warm the engine up.