i had the same prob with my 2.8... the valve tap is caused by no oil to the top of the engine.. common when its cold(thicker oil flowes slower) so there's your first prob, the valve tap is heard when??? accerlation? deaccelration? cruse idle??? and what is the pressure when it taps?? if the pressure is high and its tapping, plugged oil holes(pushrods, oil passages) if it starts tapping when the oil is really low (under13psi way at the bottom of the gauge) then its your oil pump.
Hope i helped... you all allways do
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