Assuming you are talking about the oil tube, it is secured into the engine with O-Rings and is lightly pressed in. Locate the bolt that secures the top area of the tube and remove.(usually on the exhaust manifold) Get as low on it as possible with Vise-Grips and rotate and "rock" it back and forth until it wiggles out. Put some anti-seize or silicone lubricant on the new tubes' O-Rings and line it up and GENTLY tap it in.
Why ? Just replace it.
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I've had a similar problem with my 92 grand marquis. I had to change the mass air flow sensor and replace a broken vacuum line. after that my car ran better than it ever did.
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Rear of engine near firewall.
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take it to a shop
alot
A 2000 Grand Marquis does not have struts, it uses a conventional shock/spring type suspension.
A dealership would be able to replace the key.