In my 2004 LeSabre, I have a miss. The car hates 87 octane, and 93 does a little better.
Has new plugs gapped at spec, new quality wires, its been seafoamed many months ago.

I decided to get a real-time OBD2 reader, to see what was happening. I had a code reader, but it wouldn't read real time data.

I've recorded a few runs and noticed some strange readings.
The timing seems to be extremely high, although I'm not sure what "normal" is for these cars. I've gotten anything from 5 degrees to over 40. Sometimes at idle, it is registering 34 degrees of timing. Sometimes it will drop when I give it some gas and the load value goes up, but it seems very wild. But there shouldn't be any reason it is set timing around that high of a value, should it?
Everything else seems to check out within a normal range. O2'* are active, MAF, MAP, TPS, calculated load all seem normal. There aren't any wild swings in the long term fuel trims. (of course, I haven't seen real time values since I last tuned my 87 Turbo Buick with a scanmaster).
So I'm wondering what "normal" values are for an L36 with no mods, and if the timing values are a problem. If they are out of range, what could be causing this?
As I recall, the timing advance should increase with engine rpm, mine almost seems to do the opposite.
Anyone have a set of values for comparison on an L36? Even if its ball-park stock?
And is there a way to translate MAP readings into useful vacuum readings?

That sounds about right for timing. The problem with real time data is it only part of the information. You really need a average. I'll post a picture that shows each cell has a different timing, and each cell is dependent on things like RPM and engine load.

Ignore the negatives on the timing, it'* a goofy 97 thing

That just seems the opposite of what I would think is normal.
I scanned my dad'* 98 Neon, and for the most part, timing degrees followed the engine rpm. Sitting at idle.
See, it does this sitting at idle as well. I can start it up, in park, tps at 0%, and it will still do this without a load.
I've replaced the plugs, the wires, I even went out and followed your procedure for checking the coils. (Funny, I have that exact same meter).
idk what it is. I've cleaned out the TB, the IAC, carefully cleaned the MAF, has new air filter, too. Checked everything for vacuum leaks.
It drives me nuts, because sometimes its fine, others it starts idling so low that trying to pull up a hill it starts rolling back, because it doesn't even have enough to load the converter.
I just saw that timing deal, and was hoping it would be something like the cam pos sensor would be out of sync or something relatively easy to fix.
Its got 117k on it, but at wot it pulls like a freight train. Not a hiccup sputter or anything.
I'd say EGR, but that should be inactive at idle as well as WOT.
I'm running out of ideas...

All I can think of is change the fuel filter, check the EGR, inspect the exhaust system, (cat), other then that it'* a mechanical issue, do a compression test.