Also just went through this. Got one from maf-shop.com (
https://maf-shop.com/shop/iac/porsche-iac/porsche-911-idle-control-valve-1984-1994-porsche-oe-0280140501-also-fit-924-944/ ). Manufacturer looked to be Lowe Automotive. Never heard of them before, and have only put about 100 miles on it so the jury is still out on how long it will last, but so good so far.
They shipped the next weekday, and it took about 4 days to clear customs, so all of 10 days end-to-end.
- Chris