I have an 87 syncro with a befuddling problem.  There is a low rpm flat spot
1000-2000 rpm.  This problem manifests itself only after the engine is 
warm and presumably off the cold start injector.  I have replaced the 
oxygen sensor, which has helped, but not eliminated the problem.  I know 
there is an intake leak that whistles upon acceleration.  I think this is 
causing the mixture to be lean, causing the stumble.  The only problem is 
I cannot find the leak!  I think it is in the conical gasket between the 
air distributor and the throttle body

any help/solutions/advice will be much appreciated
thanks is advance

danno