Apologies if this is in the wrong place but this is my first post after buying a yellow mk2b sporting

Just wondering why my revs bounce from like 500rpm to 1000rpm when the car is at idle? It doesn't do it when the car is cold

Also there is a loud knocking sound when going over bumps etc but on the mot the advisories were ball joints so is this causing the knocking?

Many thanks and hello to everyone

Your post should be in the Punto Mk2/Mk2b section.

I'll ask a moderator to move it. No-one will see it here.

Moderators are on go-slow.

Most likely cause is a dirty Idle Air Control. Clean the outside of the throttle body with a solvent (aerosol carb or brake cleaner is best -- sometimes you can find it cheap in pound shops or Liddle). Then remove the throttle body from the car and clean inside.

Any guides on doing this please?

Might be one in the Punto guides -- it's a pretty common problem.

Ok thank you