Vacuum Leak from Inlet Manifold

[Cobber]

I have a 2003 Explorer with the 4.6 litre V8. It recently started running rough to the point it would stall. I can unplug the inlet manifold air sensor and it smooths it out a bit. Took it the Ford dealership and they told me it was a vacuum leak in the inlet manifold and they wanted $800 Australian (approx $600 USD) to fix it so I told them to get stuffed. I have the mechanical know how to do it myself.

My question is is it a given that that will be the problem (I haven't got the error code they received) or does anybody have a similar experience where it was something else, hopefully not such a pain to fix.

I had a Ford EA Falcon years ago that told us something was wrong with it which wasn't. Instead the computer was broken, so I know not to trust what the analysers say (unless they have improved since then).

Hopefully I've explained myself well enough for someone to help.

 

[mralex714]

Check the hose running from the bottom of the throttle body to the right valve cover. If it is cracked it will run bad.

 

[Cobber]

Thanks for that. I've already replaced the manifold gaskets and that was a definate improvement. I now have a problem with it breaking down under load. I'm hoping this is only a vacuum problem, which may also be the the hose you are speaking of.