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Based on your description I suspect the shock is leaking and will need to be replaced. We should remove the trunk side trim to check to make sure the line is tight and not leaking.
Thank you for your response,Where might i find a shock at a reasonable price?
They are costly but they do make aftermarket shocks.
I recommend coventrywest.com, jagbits.com, jaguarmerriamparts.com, motorcarsltd.com, britishparts.com, welshent.com, or jaggraveyard.com as they all specialize in discounted Jag parts.