hi i have a 90 with the 19j engine, only bought last week, every now and then for no reason and totally unexpected it revs itself very high with rattle and a bang of white smoke then in the matter of seconds brings itself back to normal tick over and runs fine again, no problems starting up or on motorway journeys. I have checked the turbo which did have diesel in so i thought that was the problem cuz can smell diesel whilst driving, has anyone else had this problem or advice???