squibby

I have been having some overheating issues the past few weeks. I replaced my thermostat, and flushed out my system. Everything seemed fine unless I ran my AC. I replaced my radiator cap to help release pressure, and also added a cleaner to my coolant system. Noticed that the cleaner would cause a bubble up effect, and would gush water out of my radiator cap after a drive. last week I would top off my coolant system and was waiting till this weekend to do a flush. Well Friday I over heated again on my way to work. I let my system cool down, and drove over to autozone and replaced my thermostat to a lower temp thermostat. Ran fine to work, but my problem now is my Temp gauge is stuck way over the overheated mark, and won't go down. I tried replacing my temp sensor, and that did nothing. Tried locating any fuse that could be blown, but no luck. The sender looks ok, wires to the sender look ok. Not sure where to go from here. Any suggestions much appreciated.

Thanks