Thank you Tech71,
I suspect that it is the butterfly shaft as this had been called out by my 'guy who knows' apparently just worn and leaking air. Thanks for the link, that kit looks interesting - I haven't seen before with shaft bushings.
I'm not looking to 'boost' performance, just want to get the car running good. At present it just splutters as I change gear, especially into second gear, so need to floor it a bit to get the tickle to go, then she's fine. Rest of the engine has had a good look over hence concluding that this is the problem (Without going into a tom of detail!)
Cheers