06 RL Vent Vinegar Smell on Turns, Hills, Fast Brake

Hi, All! 2006 RL owner. I've read up on all the vent smell fixes, have had the cabin filter changed and, of course, the repair shop's vent treatment for funky smells. I've sprayed Concrobium, Lysol and Oust into the exterior intake while car ran on Vent (did not yet take off the wipers/cover to get to the direct intake as shop treated from the inside). I have, for years, run the AC on vent and not recirculate to avoid moldy evap, etc. Before I took it in for the new cabin filter and vent treatment, it was a very strong vinegar smell at the start of the AC season, worse on the driver's side, even with the residual air coming in through the vents with the fan OFF. I got a sore throat from driving with the odor with the fan off, even with the windows cracked. It was tolerable on recirculate but awful on Vent. Much worse if I made a sharp left or right turn, went up/down hills or did a hard stop. Now, after all the "fixes," it still has a residual smell AND it comes back strong with the turns, hills, and hard stops. Shop said the drain pan is draining properly (I confirmed it is draining) and it can't be nasty water sloshing in the pan.
I did find wet leaves blocking what appears to be the exterior window drain under the hood by the driver's side. I'm expecting this might have forced water into what seems to be the adjacent small air intake vent. I haven't found a good diagram of the vent system (yes, I googled) to know how its duct is configured but I'm suspicious that it might be full of funky water that releases the stench when it sloshes. ?? Any thoughts, ideas or experience with this problem? (Please no snark. I have used "search" for years on this site to fix my car without having to post so if I missed a post on point, you have my sincere apologies.)

Thanks in advance!!