turbozvh

hello all my mates gti started idling funny so we cleaned up the idle control vavle then found the lambda sensor was faulty we replaced the lambda sensor but the car now revs at 1300 rpm on idle so we reset the ecu no difference. we got a spare air temp sensor and air flow sensor cleaned the thottle control but still the same. when we start the car it revs ok until you rev it and it only drops back down after about 5 mins. any help would be much appricated cheers

justin