Hi, I have a problem with idle when cold - mostly-
Ok its a 1999 2.0 non turbo.

When i've been running for 5 mins or so, if I pull up sharply, especially after having my foot down the revs dissapear, bump, start again. I only noticed this when cold, but recently too if I have been driving hard on motorway etc and do fast stop the revs die, and it all but stalls.

Ive tried 3 garages, had the idle valve and throttle body cleaned and the oxygen sensor replaced, still exactly the same.

The last garage which was a tunning specialist in Edinburgh suggested replacing the "air bypass intake valve" So does anyone else think this is the likley source and if so any ideas as to where to get one appart from Subaru dealer - I guess it will be expensive- Help very much appreciated

 

have you changed the maff sensor,sounds like that to me,if not give david at api a call and he wil sort it,mine wouldnt idle,it would start but then die,i spent a week on it with advise from david,i checked all the basics that he told me to like maff,air flow,pipes to and from intercooler and turbo david sent a truck down to me picked the car up it was ready the next day for me to pick up,excelent service and theres not much david and nathen dont know.mine turned out to be throtle response thingy which i would have never found on my own.yours sounds like maff to me.