Odds are the roadmap for the vacum block can be had here but, I dont know the site that well. I think its in alldata as well. I've heard people talk about the rubber seals falling off the flaps inside the heater box and binding flaps too. (something to think about)
Whats the vacum like to the block as well? It should be right at manifold vacum, if not, you've got a leak elsewhere such as the vacum canister.
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.