What's the mileage on your car? Normally the timing chain should be replaced every 90-100k miles or so.
As far as what else should be replaced: the timing chain tesioner and guides. most important is the tensioner as there is a known design flaw with the original part in earlier models. The oroginal tensioner uses oil pressure to maintain tension on the chain, however, when the engine is off, there is no oil pressure. Initially this isn't an issue, however as the chain begins to stretch the tesnioner must do more. With zero oil pressure, however, it relaxes and allows the slack back into the timing chain.
Updated versins of the tensioner resolve the issue via the use of a ratchet inside the tensioner to maintain tension on the timing chain even with zero oil pressure.
although there is a known issue with the tensioners in the 2.3-16, the larger issue is that your timing chain has stretched and will need to be replaced. procrastinating on this could allow the chain to jump on the cam sprockets thereby altering the timing with disasterous results - namely contact between the piston and the valves.
The cause of all of this is the longer timing chain needed for the twincam. The extra length results in poor lubrication of the timing chain at the exhaust cam sprocket. There IS a DIY fix to deal with this and extend the life of the timing chain. you would have to drill a couple of holes into the #1 exhaust cam bearing cap creating an oil journal wich would spray a jet of oil onto the exhaust cam sprocket. centrifugal force should carry the oil to the chain ensuring that is stays well lubricated.
Of course, you could also change the sprockets and chain to a duples instead of the single, but this is a pretty expensive proposition.
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