1998 Ford Contour Overheating

Hello and thanks for donating

is the cooling fan coming on?

Pretty easy to rule out head gasket, just remove radiator cap when COLD then start vehicle. If coolant shoots out of radiator cap opening then you have cylinder head issues.

Ok since fan is working and radiator flused & tstat replaced, the head gasket would need checked next. If the gasket is good then check for excessive exhaust backpressure ( such as clogged catalytic converter) and also check for a slipping belt, leaky or wobbling water pump and radiator hoses

That would indicate a fault with the cylinder head or the head gasket, yes. A weak/failing water pump could cause overheating as well. The mixture of coolant doesn't matter, you could run straight water if you want, the coolant is just so it won't freeze and also so rust will not build up in the coolant system.

Removing the thermostat is not a good idea and will most likely not help the overheating issue any at all. The thermostat's job is to keep liquid in the radiator long enough to cool it. The manufacturer's have set a certain temp that the engine can run at before it needs to be cooled. If the operating temp of the engine is below the thermostat temp level (say 180 degrees), there is no reason to try to cool the engine down lower than that temp.

When the thermostat is closed the coolant in the radiator will continue to cool. Even if the outside temp is 100 degrees it will still be cooler than what your engine temp is. When the temp outside is in the higher levels it will take more time for the coolant to cool while in the radiator. By removing your thermostat, you create a situation where the coolant never sits in the radiator long enough to reduce the temeprature of the coolant. Essentially the coolant is constantly circulating and never cools down. You will most likely see a rise in the operating temp instead of a decrease.