I am a newbie struggling to learn to fix at least minor issues on our
cars. Recently, our 1997 Ford Escort wagon (120K miles without major
issue) has been idling roughly, and almost but never quite stalling at
stoplights after the car is warmed up. After spending the last few
weeks reading on the Internet and reading my Haynes manual, I worked up
the courage to purchase an automotive stethoscope, as all my research
seemed to point to a vacuum leak.
As soon as I started the car and opened the hood, I saw, at least for
this case, I didn't even need the stethoscope. I immediately heard a
hissing sound when the hood was raised. I saw a small elbowed "valve"
pointing into the manifold. The rubber just above where the valve
actually attaches to the manifold was very squishy. It almost looked
like it was soaked with oil (not a good sign, I guess?). The wearing
on the rubber of this substance had worn holes on each side of it (the
rubber), so that it was collapsing and I guess not allowing air into
the manifold. As soon as I pulled up so air flowed freely, the engine
ran fine. If I clamped it with my fingers, the engine stalled. It had
"MPC" on it, so I looked that up, and tied that down to a "manifold
pressure control". My Haynes manual does not reference this, and it
looks like it is long tube that starts from the front of the engine and
eventually goes into the manifold.
My two questions are:
1) How do I replace this?
2) Is the substance that has soaked and worn down the rubber an omen
of something terrible about to come my way? :(