I'm not sure it's your entire problem, but that reading is out of spec. At 14 degrees Celsius, your reading should be right around 3K.

4.7K corresponds to roughly 5 degrees C. Your car thinks the engine is colder than it actually is..... This would in theory lead to a rich condition.

Are you checking the right sensor? There should be TWO elements in your temp sensor if you are checking the right one. The single element temp sensor is for your temp gauge ONLY. The dual element sensor is the one that matters as far as how your engine runs. You need to check the value of both elements, and they both need to be in spec.

Even if it's not what's killing your car, an out of spec temp sensor will cause havoc with your MPG and performance.

-tp