Faulty temp sensor or paranoid??

Good day all!
The last few days have been very crazy! To start, my check engine light came for a few minutes, and then went out. Later that day, I did
the stomp on gas pedal five times and got the code..... (1223) Temp sensor!
Well on the way home, my low coolant code came up and my temp gauge shot up to almost the red zone, but didn't make into the red. Got home I pulled my thermostat and found it closed, and after boiling it found that it would not open. I replaced it, refilled the fluids, and then found that I sprung a leak on my radiator. Today I replaced radiator, but still had problems.
No hot air from the heater, and poor circulation, if any. The temp gauge however showed that all was well. Since I could not get all the air out of the cooling system, I turned to the water pump. Yep, that was it. The plastic pump was free spinning. I replace it as well. Now the temp is hit or miss. At times it won't leave the blue box, other times it normal. I DON"T TRUST IT. So where do I start? Where is the temp sensor that feeds the temp gauge?
Also let me say that over the last few months my temp gauge would stay around the blue box for some time, then at normal when on the highway. Now I'm afraid that I might have blown a head gasket too. The cooling system doesn't seam to want to bleed out the air. No I don't have smoke out the tail pipe, and no signs in the oil. Could this be? Am I just paranoid?
Sorry for the book, and thanks for any help/advice you can offer.
TF 1995 525i 102K miles
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It sounds like you didn't blow the head gasket, but it does sound like you have a ton of air in the system and your temp switch is not getting a good reading. Your 525i should be identical to my E36, so have you tried warming the car up and undoing that bleeder valve next to overflow tank? Once that air is out you will have to put in more water, but that is what you want...

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Well thing look ok, for now. Looks like the temp sensor is currently working. My next big project is to replace the sensors! Thanks for you help!
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