Yes.
The 2.9l valve train's oiling is feed thru the 2 center cam bearings, when they get high miles pressure starts to drop in the valve train
But in your case the collapsed lifter(s) is causing less oiling of individual rocker and low power.
If you run thicker oil, like 10w40 it can help keep oil pressure up.
Oil pressure is Back Pressure
The oil pump pushes out too much oil, all that oil can't get out of the oil passages and bearings fast enough, so it starts to back up in the main passage, where oil pressure sender is and oil filter.
So oil pressure is Back pressure.
As bearings start to wear their gaps gets bigger, this means more oil can get out, this reduces the back pressure, and this is totally normal.
But gravity being what it is it takes a bit of pressure to get the oil to the top of the engine, Valve train.
If you are using 10w30 oil, it has a viscosity of 30 when warmed up, the lower the number the thinner the viscosity, the higher the number the thicker.
Think water, pancake syrup and ketchup, they each have a viscosity, one thicker than the other.
When you use a thicker viscosity oil then it flows thru the bearing gaps slower, increasing the back pressure, so overall pressure in the system goes up.
You could even go to 20w50.
This doesn't help the collapsed lifters just increases the oil pressure for the top end.
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