My father in-law's van has a rough no-load idle and odd exhaust smell. When shifted into drive the roughness goes away. It also doesn't seem to have the power it should, but it also has 246k miles on it. It seems like a vacuum leak, but he doesn't have an owner's manual or vacuum diagram under the hood.

I did change the plugs and wires which was badly overdue, but the made no improvement. I also did a cylinder decarb but still no significant improvement. I haven't yet checked oxygen sensors 1 and 2 to check a possible catalytic converter issue.

After searching the forum, it sounds like lower intake gaskets are a somewhat common issue. I'd really like to start by inspecting vacuum lines. Does anyone know a source for the vacuum diagram?

-Rod

Not sure this is all inclusive but, it's a start: http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c1528003c531