... I do not have an oil pressure light on. I think I may have overall poor pressures under 2,900 RPMs or a section of the motor (passenger side rear, closest to the firewall.
Everyone was pretty much correct. Put a pressure gauge on the sender port. Check the oil pressure from there first. If you have a pressure problem, excluding really REALLY poor maintenance, its most likely bearings and/or pump, in that order. The likelihood there is a restriction is pretty small. Its not impossible - wouldn't be the first time a piece of gasket fell into somewhere it shouldn't.
And make sure its a good quality pressure gauge - some of them - including OEM gauges - aren't all that accurate.
Electrical sender gauges can have a PSI variance caused by electrical issues. OEM electrical senders don't last forever, either. I've had to replace my GM senders several times over the years - they just start reading incorrectly - and the one on my '02 3.5L engine has started doing the same thing in the last month and a half or so. Sometimes it reads correctly and sometimes it reads 10 PSI or so low. Sigh.
I remember reading several years ago that there is a location somewhere towards the rear where a sender could be located. I don't know if there's somewhere already taped or what. I ran across this while doing research for something else.
Why do you think you have poor oil pressure? You won't have 'poor pressure under 2900' but fine above 3000. Either you will have poor pressure overall, none, or its fine.
According to the techs, 10ish at idle and 50-60 at 3K is reasonable. I see 8-10 and 50-60 on all my 3.0 and 3.5L engines. Depends on ambient temps and oil weight.
There is a big difference between oil PRESSURE and oil VOLUME. Oil pressure keeps the bearing journals from experiencing metal to metal contact and basically keeps the cam followers (lifters) operating properly. Volume lubricates and cools the engine.
If the engine doesn't actually need 60 PSI - and most don't - a high pressure pump is a waste of HP. In most cases I've ever heard, read or seen, 40-45 is sufficient, unless you're running a very high compression engine, forced induction and/or have serious issues with detonation.
Oil volume is important (IMHO, more important), but unfortunately can't be measured and there are no available specs that I've seen.
If the pump doesn't move enough oil, areas like the rod and main bearing journals will get so hot that it will cause the oil to 'coke' - the effect you'd get if you just set the oil on fire - and you get gritty crud from the 'burned' oil that will trash the bearings, circulating through the system. Basically the same thing that can happen to oil and the bearings in turbochargers.
Not trying to be rude or trolling
- but make sure you have the right amount of oil in the engine.
Wouldn't be the first time someone's 'oil problem' was do to a incorrect dipstick replacement.
I chased a problem like this for three months and went through three dipsticks on my 'Bird. Been there, got the tee-shirt.