Mitsubishi Repair: Is it the timing or spark plug wires, spark plug wires, valve cover gasket

Question
Hello.  I recently bought a 1999 Mitsubishi Eclipse (2.0 non-turbo).  I've noticed this pinging sound in the engine. When I rev it up it stops, but starts as it is idling down.
I pulled one of the spark plug wires out and there was alot of oil on the boot.  I've asked numerous people and I hear different things.  One says it could be timing. The other says it is a bad "valve cover grommit".  
Which would most likely cause this noise?

Answer
Richard,
If your timing belt and related components have not been changed within the past 60,000 miles, have it done.  This may not have anything to do with your pinging, but if the timing belt goes go out on you while you're driving, your engine is finished.

Oil in the spark plug wells typically indicated a worn valve cover gasket; probably the ring gasket around that spark plug hole.  You can get a new valve cover gasket set at any auto parts store, but the best is from the dealership.  You'll want to get the main valve cover gasket, the "half moon" gasket, and the 4 spark plug well gaskets.  I'd also recommend getting a new oil cap gasket and a new PCV valve from the dealership as well.  All parts shouldn't run you more than about $50.  Plus, you'll want to replace that oily plug.  And you might as well replace them all.  And if its been more than 30,000 miles since you've replaced your spark plug wires, throw a new set on as well.

But if your pinging noise is more of a ticking or chattering noise, that is probably being caused by your lifters.  The lifters in the older Eclipses (89-99) had very small oil passages in them, which restricted oil flow.  Its not causing any major harm to your engine, but the noise can get annoying.  The only way to help with the noise is to clean out your lifters every time they start to get noisy.  Or the ultimate cure is to replace the lifters with 3rd gen Eclipse lifters (00-05).  

I wouldn't worry about the lifters at this point.  Just get the timing belt done if you have more than 60k miles on it, and do the valve cover gasket and other items I mentioned.  I would also recommend filling up with a tank of premium gas and adding a bottle of STP Complete Fuel System Cleaner.  That may help with the pinging if its not a lifter issue.
Good luck!