About 3 years ago my car 2.0 Duratec heater stopped blowing out the boiling heat it had usually put out. So at that time I put in an OEM Thermostat in hopes this would fix it. It did not, so I have lived with it till last week. I decided to flush out the heater core, it was clean as a new one. I decided it was my Waterpump so I replaced it with an OEM part. It is still the same, any suggestions?