I have checked the MAF it doesn't seem to be that, Did this by taking the plug out while running, the engine died which is correct. Would not of thought it could be the Lamda. The car has been not been used properly for ages been in the bodyshop. What else could it be

 

mark position of idle stability valve on inlet manifold. remove, clean and refit.
hopefully that will sort it.

 

Just got my classic wagon back, with an STi motor in now, and the idle is terrible, ( need to report this back to garage as it did it when I was shown the car when picking it up and didn't get a satisfactory response from gagarge as to why!) and as the manifold is either now an STi one or my old one on a STi head/block combo, could this cause the very poor idle I experiance? This should have been sorted when they refitted it IMHO.

Mine bounces from 500 - 100 rpm when cold, and from 600 - 950 rpm when hot, and stalls a lot when pulling up at junctions and lights.
Not ideal.....

 

Hmmm, No contact from you Neil, so this is a new one on us. It may settle which is quite normal occurrence. We clean and reset many of the engine related components and somettimes they take a while to settle.

Other than annoying it is nothing serious in my opinion. We will check it and set it up properly at the first service for you, assuming that it hasn't settled by then.

David APi Engines / APi Impreza
www.apiengines.com