Rover 25 poor power

I have two rover 25 1.4 , they are both non restricted throttle bodies but one is a lot faster than the other on pick up and rev response , I have swapped the throttle body's over this made no difference . I have a full service kit to try next , I feels as if something is holding it back any ideas ? After the service I was going to look at decat as I thought the cat maybe blocked up . Thanks

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