My wife has a 1.4 Focus Mk1.

She mentioned the other day that it was 'ticking over funny'. Sure enough, when it's warm it ticks over about 1200rpm and a bit erratically. I suspected the MAF so unplugged it, but it made no difference whatsoever, the car seems to drive exactly the same. Whenever I've unplugged the MAF on any car previously for diagnostic purposes it's been really noticeable.

I'm therefore guessing it's the MAF and the car is reverting to a cold start map (?). Before I fork out on a MAF has anyone else got any other suggestions?

I can't see that it's just developed an air leak, and there are no fault codes.