What is wrong now? Oil Pressure issue

[mdost03]

---WILL HAVE A VIDEO UPLOADED SOON---

Alright, issue started when we went on the fall cruise. While driving I was noticing that the oil pressure was reading a bit lower than usually, but still within the "safe" parameters (10psi OP = 1000rpms). Figured the gauge was crapping out as it was an Autometer Pro-Comp Ultra-Lite. Car ran fine even with the issue.

Finally got a new ProSport Oil Pressure gauge and hooked it up and it still is reading low :/

Cold start it reads around 20 psi at idle (around the same as the Autometer read) instead of the usual 60-70 I was seeing before. After it warms up, the car barely reads oil pressure anymore on the gauge and by revving it, I can max out the gauge (100psi). Seems to idle and everything fine still.

Background:
-Oil Level is fine according to dipstick
-Oil relief has been ported on the oil filter housing (did this many months ago and never had any problems, max oil pressure I saw when doing a WOT pull was 80psi or so)

My old Autometer gauge never maxed out over 100 when revving up the engine, but this new ProSport does.

Anybody have any ideas? I am so fed up with the car and it's problems, I am about to sell it.