When pulling up at a junction idle jumps up to 3000rpm fluctuates then slowly drops to normal. Mpg has gone down considerably.

I have been told it could be inlet manifold butterfly flaps??? If so how could these effect the idle speed as they only direct air into cylinders???

Nowt worse than a problem with your flaps

If the flaps are partly closed they will be reducing the amount of air entering the system, therefore making it run richer.

I have read on a thread that I can remove all 4 flaps and the spindle they pivott on, then fill all holes left by the spindle. Is there any other mod I would need to carry out ?? And do I just re fit manifold and thats it!! Job done! ??

Why do u think it's flaps what else have u checked

I haven't checked owt. To b honest I haven't a clue with cars. My local garage who always repairs my cars says it could b them and it's gunna cost £550.00 for manifold and labour on top of that. There is a rattle sound from it. And dissapears when vacuum pipe is pulled off. I was thinking that if it's possible to do away with the flaps completely then why is it affecting my idle speed??

if the swirl flaps are rattling its best to remove them before the engine eats them,as for the idle speed rising look for an air leak in the PCV pipes which would have this effect.

I think u have two separate issues here noisey flaps won't cause ur issue it's something else causing it to rev up but best off either breaking out flaps or replacing manifold