civic-vti

The last 8-10 months i noticed my car to bog every time i let of the throttle and let it roll with gear andthe time it gets below 2000rpm it starts bogging.Another thing is that it runs colder.Last night i was driving at the highway(70mph) and the temperature gauge went almost outsite of the blue line(cold site).Now i've been told that the EGR will let exhaust gasses pass to the intake manifold and minimize the fresh air and fuel that will go in the chamber, since some of that volume it will be taken by exhaust gasses the combustion will be less powerfull and the temperatures in the combustion chamber lower!
Can this be,because of the EGR valve?How can i fix it?How can i clean the EGR valve?