fan working.
fan working.
OK, just to let you know ive solve the problem. it was the water pump, the housing had come apart on the insidem, which in return broke the pump itself. What should of been just two parts, ended up being four parts. thank you all for the input.

l have a 99 cougar and they arent good cars. Looks good though. l will never go domestic again

is the fan working?

It could be the water pump, or a partially blocked radiator.

2.5 litre water pump has a plastic impeller pressed on to a steel shaft, the impeller has been known to crack thus not spinning with the shaft
If the impeller does not spin then coolant cant be circulated
Just a problem Ive seen many times

What led up to the new thermostat. Was it overheating before the thermostat change. You're talking about a very vintage car. Have you changed the hoses on the car. The hoses can collapse and cause the car to heat up. What you have to do is run down the list and make sure you've done all that is necessary to the car. The impeller blades on the water pump could have lost or disintegrated teeth. Many questions and things to look at.