I need some suggestions on valve noise.

My 1995 750il with 110,00 miles (this car is not driven much) has developed some upper end valve noise. Let me explain how it has progressed.

On cold starts, there is definite starvation to the top end. When the symptom first started, i start the engine - it sounds like upper end starvation but would quickly settle in and run normally. Drive and do errands, come back and it repeats the same process.

Then, it progressed to constant valve clatter in a few lifters. It does not go away now.

I have checked the following areas. Oil is being retained in the filter housing, but the filter and housing were VERY sluggy. I have checked the oil pump. The oil pump bolts were all loose. One was laying in the pan. I tightened all the bolts and reassembled and am still having the same symptoms. There was a slight bit of sludge in the bottom of the pan.

I am not getting instant solid oil delivery to the top end.

I am thinking that some oil delivery route is clogged to the top end?

\Where should i go from here? Thanks.