Hi I have a 1987 hymer with a 4 speed auto box and full vacuum control but has started changing gear at high revs so put a vacuum gauge on it and from feed I'm getting 24" pressure but when I put on other side of vcv I hoped for around 14" but only got 6" Max so cleaned the vcv with brake cleaner and reset it but still the same so is the vcv in need of replacing as cannot find 1 anywhere in UK so can any body tell me if it does need a new one and were I can get good secondhand 1 or a new 1 thanks Dave will look at replys when I get up as 1am over here again thanks Dave