Well, I'm on a roll now so here's another one. Carburettor English spec 308. As per loads of posts on the issue of airbox intake and removing the fiberglass wadding and rusty tubes I cut out all the stuffing and replaced the old filter with a K&N replacement to help breathing. Result - the car that used to idle nicely from cold with no choke now has to be coaxed into life with much accompanied popping and coughing for at least 5 minutes before it settles down to a consistent 900 RPM.Then on the road for the next 5 minutes it'll pop back on the overrun till normal service is resumed and it starts to get to temperature.Question. Am I correct in thinking its only the idle mixture thats gone lean or could I be looking for new jets as well? I did the colourtune/balance tweak at the time and the mixture seemed OK when hot.I know a rolling road session is the way to go but have any others out there had a similar experience?