Over heating when RPM is icreased from 2000 RPM

You may have a bad thermostat that is half way stuck and needs replacement. Check the coolant level. You may also have a problem with the fan. Make sure it is operating by letting the car sit until it reaches operating temperature and the fan comes on. If the fan does not come on you may have a bad fan relay, coolant temperature sensor or the fan itself could have a problem.
You may also want to have a coolant system pressure check done to endure the systme is holding proper pressure. If you have not changed the anti-freeze every 24,000 miles or 2 years that could have caused corrosion in the system or a leak. So also look down into the radiator with a flashlight and see if you can tell if there is corrosion. If you have never changed the anti-freeze, change it. The conditon of it will also tell you if there is corrosion in the system. You should flush it before adding new coolant mixture.