Buick Century, diagnosis code P0300: needs a timing chain?

Hi Everyone, The 'Service Engine Soon' light stays on, and my mechanic (a very sharp guy) thinks the P0300 code - and the many engine misfires on cylinder 6 -
mean it's time for a Timing Chain. (This 1996 Century has 121,000 miles).
He's tested the coil, wires, and spark plugs: all seem okay. He's performed a 'cylinder balance test' (?), and it passed. Compression tests on cylinders 2, 4, 6: good pressure. He doesn't believe #6 fuel injector needs replacing.
He's noticed the timing fluctuates at idle, but stabilizes at higher RPM. The engine misfire also seems to go away at higher RPM.
Any other opinions? Thanks!
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Catality converter comes to mind because they are know for this with out giving you any heads ups. tell him to do a back pressure test he knows what i am talking about also the camshaft sensor in this things goes expesially with that kind of milage. good luck

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rbolms wrote:

If your doctor said it was time for a new heart because you were 55, would you say, "Go ahead"? He could check the slack in the chain and know whether it's worn or not. Move on from there.
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Galiano and Bundy: Thank you for your advice.
Cause was timing chain, now fixed. Case closed.
Regards, Rick
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