I have a Dodge Caravan 1996 that overheated last month due to a bad thermostat. I replaced it, changed oil and PCV valve but from an average of 22 miles/ gallon has been dropping mileage and now is making less than 19 miles/ gallon…I also find that the power is not the same.
Over heating can damage a lot of things in a car.
Have you had a compression check?
Not enough info is known to make much of a guess. You did not state mileage, any Check Engine Light on, exactly how long the engine was overheating, etc.
JMHO, but in a shop setting running a compression test would be the first item on the agenda given the overheating and the ensuing complaints.