Thank you, Chris.
Something I didn't mention, which may have relevance - my exhaust isn't standard. I believe it to have been fitted by Krazy Horse at some point prior to my ownership (I have tried to contact them for clarification but they never respond or call back) but the air filter and ECU are all standard as far as I am aware. Could that have anything to do with it?
Appreciate the advise, it gives me somewhere to start.
