Getting there!
It's now started misfiring (LOLz) immediately at start up. Still idles awful.
Changed the coil pack and spark plugs - no difference.
PLUGs are very black.
Changed ICV to my spare (magnetti) - no difference.
Blocked off the throttle body with my hand - car stalls (no air leak)
Disconnect the map sensor again - car idles OK.
Was about to give up - just thought to disconnect both lambdas.
IT IDLES! and revs normally. No misfire
When I said 'immediately' about the misfire I mean, the first time I started it, it didn't do it. it warmed for about 1 minute, then subsequent restarts it had a misfire. So that sounds lambda to me. Wonder at what water temp the lambda closed loop kicks in...
The front lambda is possibly China (but it's new) and has a green connector. Apparently a green connector means post cat... so that would be wrong then. The current post cat lambda is green also, so I can't even swap the fuc*ers.
New Bosch Lambda on the way. Listed as 'front' lambda it has a black plug! brilliant. Good job I'm not colour blind.