97 Olds Bravada misfire p0300 p0304

A month ago my 1997 Oldsmobile Bravada was running great. Then it started idling rough out of nowhere and wouldn’t start at all; all in one day. So to start with I ended up determining that my starter was bad (coincidentally) at the same time as the rough idle. So I replaced the starter. Then I did a complete tune up, plugs, wires, cap, button, air filter, oil change… All things I considered normal and needed done anyways.

After the tune up I still had a rough idle.

Finally I got a check engine light the next day.
Got it scanned – and got p0300 code.

So I tried replacing cap and button to ensure I hadn’t received a bad one from the parts store.

After replacing the cap, and button for a second time and driving a while – No Change.

So I figured my options were – Distributor, Mass Air Flow Censor, ICM and or a lot of the normal run down associated with only a p0300 (random multiple misfire)code.

So I replaced the MAF (Mass Air Flow)
No Change

After another vehicle scan I was now getting a p0304 code.
In the mean time I have also then realized I did not have overdrive any more.
This must have started at the same time as the misfire issue because prior to the misfire I did have OD for a fact.

So a friend of mine who is a transmission rebuilder got his Genisis scanner and we went for a ride. I could now see that my problem was indeed in cylinder 4. He also told me that I wasn’t getting “lock-out” and that the no OD problem may be because of whatever was going on with my misfire. He said get the misfire right first then we would see if that changed anything and look at it again if I still had no OD.

So for my next step I went and got a inline spark tester.
I was gettting fire on cylinder 4

So I got a compression tester.
I only got 80-85 PSI on cylinder 4 when I tested it.

The spark plug I pulled on cylinder 4 was really white hot looking like it is burning lean by the way and this was a plug that had been in there only 2 weeks or so since the tune up.

I then put a new plug gapped correctly (0.60)in cylinder 4.
After about 20 minutes of driving the check engine light went off, the vehicle felt like it smoothed out from the rough idle, and then OD (overdrive) or lockout as my Transmission friend called it, did indeed come back.

So my question is,…

Is this only temporary?
I feel like the pressure in cylinder 4 at 80-85 PSI wasn’t correct.
and the only reason it seems to be o.k. at the moment is because of the new plug.
I feel like after the new plug gets hot/ or burns lean again, it will return to a misfire.
Would it be worth it to go ahead and do a dry and wet compression test still on all cylinders and see where I land or should I ride it out a few days and see if the misfire returns?

I know this was long but I did not want to leave anything out.
Thanks for any help and advise!