Hi Everyone, I have got a 2.2 import 4th gen prelude, When I am driving the car loses power when I idle at 30/60 mph,but when I put my foot down it cuts back in again and gains power no probs? it doesnt do it all the time, but also their isnt a perticular time that it does its, it can go for days with out doing it then there is days that it will do it constantly

i have just had a Stainless exhaust fitted but didnt get the cat changed, buit have been told that this defo needs changed so getting it done, Can this be the problem?? Please Help,