hi ive just bought a mk1 galaxy 2.0i dohc when I start it it will tick over fine but if I rev it the revs take forever to drop back to tick over I have spent the day checking all the pipes etc for air leaks and have also checked and cleaned the throttle thingy which looks like it had been cleaned recently any ideas wot this problem may be or wot else to try any suggestions welcome oh before I forget it also feels like its holding back when its up around 60mph or going up hill .