I have a 92 e-150 with a 5.0 engine. I recently changed the alternator and since then my gas mileage has dropped drastically!i have noticed that between the smog pump and alternator is a canister about 3" in diameter. There is a vacuum boot coming off the bottom of it with a red vacuum tube that is broken. I have searched tirelessly trying to figure out where it is supposed to go but i can find nothing! When i discovered the tube it was pointing straight up the passenger side of the engine towards the hood. It is about 7 inches long at the break point. Can any one help? Thank you in advance

From mid-80's to mid-90's 5.0 motors used the TAB/TAD valves along with smog pump to direct engine vacuum. This post on Fordtruckclub.net had an explanation of that setup and pictures of vacuum routing: http://www.fordtruckclub.net/forum/showthread.php?p=48736 . You can pick up 5/32" vacuum hose at any auto parts place to make your repairs with.

I looked at the article but had a hard time identifying some of the lines and the components. His engine is from an f-150 whereas mine is in an E-150. It is very difficult to follow the vacuum harness in my van between the dog house and firewall. Ford squeezed the motor in there pretty tight on the passenger side.Also,In his article he talked about the routing of the tab/tad to the catalytic converter. There isn't one on my van. In fact, as I was looking underneath the van, I noticed a tube about a half inch in diameter that someone apparently cut off with a cutting torch and just left hanging. I have no idea what that is for but I had it brazed shut thing it was the cause of an exhaust leak and a possible vacuum. I'm thinking it fed into the catalytic converter? At any rate, I am still wondering what I could have possibly f'd up when i changed the alternator. Am I on the right track in thinking vacuum leak? or should I be looking somewhere else