I have a Toyota aristo 2jzgte non -vvti registration 1994.[JZS147] A fault has developed regarding high idle from cold start ie instead of initial say around 1700 rpm it slowly increases instead of dropping as the engine heats up?[ once warm if rpm at idle was 1000 rpm it would clear by switching engine off/on[bringing idle to normal at hot 650-700 rpm ,but now no longer the case] On engaging auto box drive the revs drop to around 1100 rpm and the car really drives on it`s own. In park the engine surges/hunts between 1500-3000 rpm. I changed the IAC Valve ,but no difference. Toyota cannot fix as being an import, but did say it was a vacuum leak .Also car has a mines ECU. Disconnecting/reconnecting battery no longer clears high idle either. ie ECU not relearning? Can you give me some help . Thank you , Best regards, Alex.