[Bladecutter]

I am having a hard time understanding what you have done so far with your Boxster.
If I am reading this correctly, you have done the following so far:

You have replaced the Oxygen Sensors before the first catalytic converters, and tried resetting the codes, but the CEL comes on after 50km every time.

You have disconnected the MAF from your car, and the car then starts very easily, and is very responsive between 1k rpms and 5k rpms.

You have tried cleaning the MAF - are you using electrical cleaner, or actual MAF cleaner?
Try using actual MAF cleaner if you used something else.

Here's something to try.
Keep the MAF disconnected, and clear all the codes.
Drive your car for 50 to 100km in that condition, and see what CEL codes you get this time. If you don't get the 1128 and 1130 this time, then you probably just need to replace the MAF, and should be fine after that.

Also, if you can, let us know what the part number on your MAF is.

BC.