please can someone help

?? if i drive my car nice and slow and normal its seems ok , but if i put my footdown or when i come off the motoway it starts reving itselfs constantly wen i come to a stop , but if i turn the engine off then back on again it goes back to normal .... ive changed the idle control valve , water temp switch , lambda sensor , crank position sensor , dizzy cap , rotor arm . I really do need advice of what the problem could be .