Thanks for all of the input guys.
Dean1484 - thanks for the offer. Once I have sorted the issue out and have more faith in the car I may take you up on your offer regarding compression testing.
I had replaced the T-stat with an OEM piece a few years (only ~3,000 miles) ago. I replaced the water pump, the coolant fill neck and all of the hoses at the same time.
I did not get a chance to check for leaks around the injectors with carb cleaner this past Sunday. This coming weekend I will give that a shot and will also check out the coolant sensor, the coolant sender, and the air temp sensor.