Firstfives.org

I've noticed lately my car is doing this:

I start the car and, in park, I idle at ~1050

I blip the gas and idle rests at about ~1350

AND if I put the car in drive or reverse, and then park again, Idle goes back to resting at 1050.

I'm so stumped - I have a feeling this is something one of the e12 geniuses on here might say "oh thats x y and z".

I want to buy you all beer

EDIT: PS. I know its not my AFM, I swapped it, same issue
I also know its not my vacuum retard- it does the same thing at higher RPMs with the vacuum retard disconnected.

EDIT AGAIN: Its not my idle control switch; I also have nothing bothering my throttle linkage. I don't think its my distributor at all. I had this issue before swapping to the 528i distributor. Maybe both are sticking? It is consistent- blip gas, idle lands higher than it should. Put in reverse, back to park, idle goes back to 1050 again. Putting it in gear and back in park clearly resolves the issue, I just don't know why. Could it be a sticky vacuum limiter? I disconnected the vacuum hose from that, same issue.
Swapped my ECU with a spare, same issue. Combo relay is just two years old, and I don't see why putting it in gear would rectify any issues with the combo relay.

I am completely and utterly STUMPED.

.... I will entertain wild or educated guesses!!!

I'm leaning towards something wrong w my "vacuum limiter," my brake booster check valve, my TPS, or some unseen very sensitive vacuum leak that opens when I give gas and closes when I drop the RPMS.

Also, while I am driving the idle is also up, say if I'm stuck at a light...
At first, I thought it was my AAV which I fixed last year, but if it was that, I wouldn't be able to rectify by changing gears. And the AAV closes all the way once the car is warm..

I think it stopped... I suspect it was my vacuum advance but the TPS was also giving me an intermittent connection... I sanded clean and bent the blade a drop. We'll see!