Another question to all the experts out there : on the 240 (B230F engine),out of the Lambda sensor and the AMM, which one of them is the primary sensor? Are there any other sensors which are primary sensors?
On another issue, the car runs very well but the idle currently runs a little high, feels like 1200 rpm which actually drop to about 1000 after about 5 seconds but it still feels too high. Swapped AMM, lambda sensor and air temp sensor for known good ones, no difference. Checked the flap valve in the air filter housing which was oxydised and cleaned that one up. Occasionally, the car would hiccup a little upon acceleration (especially when cold). Any clues as to what could cause the high idle? (A leak?). Should I have a look at the coolant temp sensor (not done yet)?
May I just take this opportunity to thank everyone on this forum for their input, I've learned loads on my 240 (and still am) and am keen to go to great lengths to keep it on the road for many years to come.
Thanks again, look forward to your comments on the above.

Cheers

Pierre