High revving when changing gear in mk6 fiesta 1.25

Hi there 

I was wondering if someone could help me out with this problem on my car. I've owned my mk6 fiesta for around 6 months now and consistently from the first day it's had an issue with revs staying high for a few seconds when changing gear which makes for a lumpy gear change.(most noticeable in first to second)

I've already run a check on the cars computer which brought up no faults so was wondering if it had anything to do with the throttle position sensor or throttle body still? 

I've heard cleaning the throttle body can resolve similar issues but I'm unsure to how effective it would be.

Any knowledge on the matter would be appreciated.