4.4i X5 Misfires and Stalls, no DTCs

[Drdetroit455]

’03 BMW X5 4.4i with ~110,000 miles. I tried searching thru other threads, couldn't find good direction for the following:

Bought used a ’03 X5 4.4i a couple months ago for my wife. She is the primary driver. Drove great until just a week ago. Big change in one day.

Stalls at idle, bad misfire (bucks hard). Feels > than one cylinder.
When this first happened I suspected bad gas, she had just filled up earlier that day and lost her gas cap the same day. I operated on only her description for the 1st few days.

I started driving it to see if I could diagnose (20 years ago I was a ASE Master Technician with Advanced Drivability Specialist, so not totally green. Just with BMWs).
The only DTC shown is the EVAP one due to the missing cap.

Seemed to run good when 1st started, then would get worse on my half hour drive. Wants to stall often but could keep running using two foot driving technique. Under acceleration there is an intermittent stumble, like whole engine cuts out for ~ a second, randomly at different RPMs and loads. Sometimes multiple times over a short term (20 seconds), then it recovers and will eventually repeat again with-in 5 minutes. Service engine soon light never came on. But also runs strong for short terms between issues. Yesterday’s drive home was the worst, barely made it. Went to drive again this morning expecting it to run good at first, but I could barely get it started and down the street. Stopped and opened the hood and disconnected the mass air flow sensor (per what I had read here). It ran better, did not stall but I also kept driving using the two foot driving technique. After cooling for 4+ hours at my destination, plugged in MAF and read codes. Had air temp code, MAF code, and both banks to rich code. Cleared all and started and let run sitting in park. After about a minute idle goes way down and wants to stall, it recovered from this 5 or 6 times spaced out for ~5 minutes then it finally died. Service engine soon light never came on and no codes are present. Issue is still present when I drive.
Can be hard to restart, must give considerable throttle. Has feel of loading-up (too much fuel) from exp. riding 2-stroke motorcycles. Does not have excessive fuel smell.

I have a new gas cap on order and will install tomorrow. Gas has been purchased twice at two different locations from original day when issue occurred. I also thought I ruled bad fuel out as an issue when it would run great for the 1st 3 or 4 miles of my drive.
From this groups experience, what is my best way to proceed before seeing a BMW dealer? My scan tool will not show engine data, only reads DTCs.
Thanks in advance!