[thstone]

You've already done the most obvious things. The only remaining item I'd suggest is to check the AOS and associated tubes (including the oil fill tube). They can also leak and act as air source. When you remove the oil fill cap, does the engine stumble and then recover as expected?

I also still worry about the MAF. You could try clearing the codes and disconnecting the MAF. Then drive the car. I would expect the engine to run poorly at first but then improve. If the problem is the MAF, the codes won't come back. If you have an air leak (or something other than the MAF), the codes should re-appear.