Mine runs a just a tad over 200 if the factory guage is accurate. I wondered if that was normal, and considered asking this same question here. Sounds like it's ok. I may put a 180 t-stat in.

 

So if I put a lower temperature thermostat on would my truck run more better or efficiently?

 

Yes and no. Using a lower temp thermostat will make the engine more efficent by way of running at a cooler temperature and it will also cause a fair power increase for short money,but you may notice a small loss of fuel milage. I would probably go with the 180 degree as apposed to the 160 as not to mess with the air/fuel mixture too much.