1998 Stratus Valve Tap

I have a 1996 Stratus with a 2.5L Engine. I has about 90,000 mikes on it and has just developed a valve tap, however, the valve tap comes and goes. The tap goes away when I raise the engine rpm's and usually comes back when idling. I've tried flushing the engine and changing the oil. That does not help. Any ideas would be appreciated.

When the ingine is Idling the oil pump is turning slower and giving lower oil pressure than when the engine revs up. When the engine main bearings wear then the oil, which is fed to the crank mains first, leaks back into the crankcase bypassing the rest of the engine and starving it for oil. The valvetrain then gets noisy as the valve guides wear (v6 is a japanese engine) and the lifters get starved for oil. When the engine is reved up the oil pressure rises and enough oil volume is pumped to overcome the loss to the crankcase and the lifters get their oil and they quieten down.
Short version: engine is tired.
You could try a thicker oil (ie: diesel 15w45) but this will not repair a mechanical condition.
RG