Thanks for discussing it chaps! I gave it all a check over today, the MAP sensor mounts straight into the manifold, so no pipes leading to it to get blocked.

Throttle body was mounted with new seal so there is no air leak from there.. the vacuum pipes for the fuel pressure regulator and brake servo do come from the inlet mani though. Upon inspection of the hose attachment for the brake servo pipe, I saw that the clip wasn't tightened, and the hose was really loose on the nipple (could easily be twisted round).

Under high vacuum, do you think air could be sucked into the manifold from this poor connection, and lower the pressure in manifold, causing MAP to tell ECU to over-fuel?
I've tightened it but not actually been able to test the results.

If not, how likely do you think that what is illustrated in the following pics could be the cause? Bearing in mind I am failing on double the CO limits, and only 0.01 too much lambda..





Pretty suspect?