Thanks , have new fuel pump,filter, plugs, leads, cap checked, air filter,choke setting, mixture and etc; it's the change in idle from fast to slow , surgeing all the time that makes me think of a vacuum or air problem, have spent hours trying to resolve this and everything I try wont fix. The main problem I have is not understanding what the wonderful valves and heavens knows what on the anti pollution gear actually do and work. My workshop manual is not much use, trys to cover too many models.. a diagram of the various pipes and brief description of what does what would help a lot, can't track one down. Nearest Subaru dealer is three hours away, why am trying to fix.. Thanks Lang