10-4 there is much more than 15degrees difference between upper inlet and lower outlet. More like 50 degrees when I checked it, actually I think it was more then that even. I would speculate that there should be more than 15 degrees difference between inlet and outlet, or it just wouldn't cool enough! I want to say it was about 130 incoming and about 65-70 going back out to the engine. I would think that only a 15 degree difference would indicate that there is a problem, not that everything is working alright, but I'm not an expert.
Either way, like already stated, the problem was the actual dash gauge and not in the engine. Mechanical gauge fixed everything and now it stick right around the 200 mark by the gauge and by the IR temp gun as well.