Obviously you don't have everything disconnected or you have a short to another circuit. Again, do you have a cassette player in the console or CD changer. If your 0.5A draw in post #3 is real and your 2A draw is bogus and just times out after a while (reverting to 0.5A), then you could possibly be chasing the wrong circuit. Either 2A or 0.5A would run you battery down quite fast. I would start by doing the parasitic draw test properly. If it stays over 2A, then I agree you are on the right circuit. If not then you need to look at what is drawing 0.5A. Are you seeing what I'm talking about?

You will need some additional equipment (more than your fuse) to do the draw test properly. How else are you going to keep power to the vehicle through your meter while disconnecting the battery?

Hopefully this vehicle does not have an aftermarket remote start installed?

I once had an customer's Olds Toronado where the windshield wipers would take a swipe across the windshield once every time you stepped on the brake. Problem was a blown fuse and a bad tailight bulb backfeeding voltage through another circuit which ended up tripping the intermittent wipers to take a swipe. I once had a customer's K1500 where it would die every time you even tapped the brakes, but only if the vehicle was rolling forward. Nothing when sitting still or backing up. Was a bad starter solenoid plunger tipping forward and shorting out the ignition system. Once had a customer's Buick Skyhawk that would start, run for 2 seconds, and immediately die with no fuel injector pulses. Was a bad alternator overcharging severely and freaking out the ECM, which then shut down to protect itself. Moral of the story is that automotive electrical circuits do strange things, and nothing may make sense until the cause is actually found and repaired. When faced with something that doesn't make complete sense I have found that it is best to back up and absolutely verify the most basic things first (things that do make sense) before trying to move on to a conclusion.

 

It has been an interesting month and my attention was focus elsewhere until today.
EDIT: It has been a week, and I can confirm the parasitic draw is gone. the battery stays at full charge and the car starts like a charm.
To answer previous questions, I do indeed have the factory amp and the CD changer in the arm rest.
There is no aftermarket remote start or keyless entry system.
As per LesMyer's strong suggestion, I did a voltage drop test to find my parasitic draw instead of the old school amp test.
I had unplugged the door's switch last month, so opening the door did not trigger anything, and I did my test after well over 1 hour of the car 'resting' after driving it, with a battery fully charged.
The test took me once again to fuse #19 "DBO BATT", with a voltage drop of 3.2 Millivolts at the fuse. As per the mini fuse charts from power Probe's website (https://www.powerprobe.com/fuse-voltage-drop-charts) It actually translates to a a drop of 0.7 Amps. I started with the radio, and the voltage drop test at the fuse went to a nice 0.00 millivolts.
Last month, I only unplugged the black and white connector on the radio for my test, which probably was another mistake. This time I unplugged everything and had the radio on the passenger seat.
I don't know if this will solve the whole issue, as I may have more parasitic drains, but I sure am glad fuse #19's aka RDO BATT mystery is now solved.
I did not find any draw on any of the other fuses, either underhood or on the left side of the instrument panel.I am confident I'll find the car starting fine tomorrow morning. [edit #2: I still have some fuses unplugged, related to 4wd so I don't know if those will create drain issues or not yet]
Thanks LesMyer!

I'll be back soon for the 4x4 issue on another thread.

 

did you ever fix your problem ? I’m having the same exact problem