when i start my car it revs right up and it doesn't really come back down. when i reverse it revs badly and when i change gewr especially into 2nd and 3rd it over revs. does anyone have any ideas?

first check that all the vacume pipes from throttle body to cylinder head are ok with no leaks as this would upset the maf and produce a rich mix then it could be a throttle position sensor problem or its voltage /idle controlle valve requires cleaning you dont say how high the car revs,on 1999-2000 2L zetec e engines there is a known fault with the idle air valve which also causes over revving