1997 4.0L SOHC recent rebuild oil pressure drop

[genealogyman]

Just rebuilt a 1997 4.0L SOHC which initially had some timing issues. Now when cold runs OK but occasionally stalls when shifting into low gears. Oil pressure OK while cold but once warm and RPM drops below 1000 (natural idle) the needle flutters wildly and then drops off completely.
Question 1. How much does oil pressure/flow depend on the manifold vacuum?
Question 2. How much does the stability of oil pressure depend on the timing?
Question 3. How "off" can timing be and be "OK?"
It is a big job to time it and I can make further adjustments but I lost our other vehicle to a blown tranny and it won't be back into service for at least another week.

 

[david4451]

1. Vacuum from inlet hardly affects oil pressue.

2./3. Oil pump is driven off jackshaft, I doubt it has anything to do with timing being 'off'.

How much of a rebuild did you do? When I stripped mine down I found a problem with the oil pick up attachment to oil pump.

Search:"Possible culprit for chain rattle/bouncing oil pressue gauge +"

 

[genealogyman]

Found the issue. Pulled the lower oil pan and found a bunch of gunk had plugged up the screen on the oil pickup. Pulled it off. pulled the gunk off, changed the filter and put it all back together. Oil pressure problem appears to be better.
Now Question #3. How much can timing be off and still be "OK?" I guess what I am asking is how much do the various sensors compensate for the timing if it is a little off? I ran my AUTEL tool and Spark advance was at 18.5 degrees at idle. and it seems to idle ok. However, as I get to about 2000 rpm I can hear the engine rattling a little like "gutless uphill knocking" I just wonder if at the higher RPM if we have passed out of where the timing can be compensated for? At just over 2000 RPM the spark advance has increased to 28.5 and the MAF reading is at 32.91 g/s It seems to me they are doing what they should be but I work up a canyon and need this to get there. I am concerned if I put it under that kind of strain I could blow the engine. I have purchased the OTC 6488 kit and I am ready and willing to do the timing again, (last done with the full kit when the engine was out under head job.) Just don't want to tear it apart again if that is not the issue.

 

[donalds]

The rattling is the rear passenger side trimming chain rattling due to a broken guide

It will rattle at 2000 to 3000 rpm

Sounds like marbles in a can