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Just for comparison information, my mechanical oil gauge is connected to the rear passenger cylinder head, and I get no fluctuation of any kind at idle, or any rpm for that matter - truck is low mileage all stock 54K 5.4 3v.
May be possible the fluctuation you see is due to oil connection tapped at the usual spot by oil filter (so close to oil pump and bypass spring. )
Funny you mentioned this as I thought I was alone! My mechanical gauge does bounce a bit too between 25-30 (hot idle). No engine noise or rattle at the same time - just a quick little needle bounce. I just figured it was air in the line or possible electrical glitch in the gauge. My engine runs and sounds excellent, so I don't worry.
PS: I put the M340HV pump in mine. I was going to use the M360HV but decided against it. The only difference is the pressure if I recall (and the extra expense). The 340HV is working great in mine. Using 5W-30, I get 25-30 psi hot idle and 60-70 cold even with all the damage my engine has. I realize my gauge isn't top-notch and 100% accurate, but it's close enough. Certainly better than the idiot gauge our trucks came with.
Stock oil pump. I have a mechanical gauge plumbed into the fitting behind the oil filter, the needle has a "bounce" of about 1 psi at hot idle that seems to coincide with rotations of the engine. At higher pressure (75 psi engine cold) there is no noticeable bounce.
Just for comparison information, my mechanical oil gauge is connected to the rear passenger cylinder head, and I get no fluctuation of any kind at idle, or any rpm for that matter - truck is low mileage all stock 54K 5.4 3v.May be possible the fluctuation you see is due to oil connection tapped at the usual spot by oil filter (so close to oil pump and bypass spring. ) 
That's the spot I'm wanting to install my electronic Glow Shift gauge, but seems rather difficult to get to so I'll probably just put a T value on oil pressure sensor plug and call it a day.
Just for comparison information, my mechanical oil gauge is connected to the rear passenger cylinder head, and I get no fluctuation of any kind at idle, or any rpm for that matter - truck is low mileage all stock 54K 5.4 3v.
May be possible the fluctuation you see is due to oil connection tapped at the usual spot by oil filter (so close to oil pump and bypass spring. )
I use a GlowShift gauge too and I'm plumbed in at the filter with a 'T' fitting. Easier to get to it when you have the front cover off and steering pump out of the way. I also had to replace the gasket on the oil filter adapter so it was a good time to hook the gauge up. Trying to get to the port when everything is put together is a MAJOR pain - especially with Sasquatch hands like mine! Find someone with Keebler elf-size hands to give you some help if you have to do it this way.
I've heard the head port is much better to use but I had a hard enough time with the valve springs and rockers back there. Someday when I get a new engine I'll move my gauge to that port when the engine is out. For now I don't mind the trigger bounce.
Don’t know if I should start a new thread but anyway.
Doing the timing job on my 2010 5.4l, I finally succeeded in removing the front cover. There’s signs of rubbing against the cover. This confirms that the job needed to be done. Please feel free to give inputs if you have seen that problem.
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Appart from passenger side chain rub, I have found same side tensioner clug with debris and this;
