Overheating problem

My car keeps overheating even though it has had the thermostat, head, and head gasket replaced. The radiator has been cleaned. The fan and water pump have been checked and are working fine. The firing order was wrong, but has been fixed. I don’t know what else to do. The car runs fine without the thermostat in, but once it is in the car overheats. I don’t get it. Could my brand new thermostat be bad? Or is there something I haven’t checked yet? Oh and there are no leaks anywhere, so that isn’t the problem either.

Yes. You may have gotten a bad new thermostat. It’s happened to me a few times.

Tester

What tester said or you have put the thermostat in upside down (the bleed port goes up at the highest point) or backwards (if it will fit that way).

Thanks. I am pretty sure it is the thermostat. I checked it last night and it should be opening up around 180 but it doesn’t seem to open up til around 200-210. So maybe the temp is off in it.

OK, what tester said. Thanks for the feedback.