Chrysler Repair: Chrysler Newyorker 1994, haynes manual, vacuum line

Question
Hello Roland,

My Name is Danny Merta and i am writing to you from Calgary Canada.
I have a question in regards to a 1994 Chrysler NewYorker.
My girlfriends grandmother owns it and it has 62,000 original km's.(30,000 miles)
It seems to shimmy and shake when driving and even when you are stopped in gear it seems to vibrate.
Would you know what could be the cause?
One mechanic said it needs a tune up,and she had that done and that did not seem to cure the problem but i think they usually sucker old people in to make money.
But if you could think of what could be causing this shaking.
I would appreciate your feedback,thoughts and ideas
Thank you for your time
Danny

Answer
Hi Danny,
The first thought that comes to mind is that an engine mount is loose of fatigued. I haven't worked on the New Yorker but the Haynes manual says that you need to raise the engine up slightly, just enough to take the weight off the mounts. You raise the vehicle and put the front end on jack stands. Then you use a floor jack with a large piece of wood between the jack head and the oil pan so as to spread the weight of the engine over a large area of the
oil pan, and lift the engine slightly. Then you check all the mounts for cracks in the rubber or separation from the metal plates, and also try to check for movement between the mount plates and the frame or engine (use a pry bar or large screwdriver to move the plates) and if you get movement lower the engine and tighten the mount fasteners (45 ft-lbs). To replace a broken mount you need to keep the engine supported, then remove the 4 fasteners (both to the engine and the frame) and then lift a little more on the engine so the bolts clear far enough for removal.
The fact that it feels loose at idle and when driving makes me suspect the mounts.
Other vibrational cause could be a vacuum line leak (inspect all the plastic and rubber lines on the intake manifold for cracks or disconnects), or a sticky egr valve(observe the rod inside the mushroom cap for motion when you rev the engine), or a clogged air filter. Finally would be to do a compression check on the cylinders to see if one of them is not working well due to a valve problem, or a blown head gasket.
Let me know if any of these are useful to you. It is good of you to help out in this situation.
Roland