Negative on the EVAP codes. You have a good puzzle. I have one too I'm dealing with on my SRT6.
If your car is a N/A you should consider machfivecrossfire vacuum leak above.
If you have K&N air filters, perhaps some oil has gotten to the MAF element and is causing that code. Cleaning the MAF with a MAF cleaner would clear that up.
As it is getting worse perhaps you should consider a back pressure test on the exhaust system. It is an easy test if you can get the forward O2 sensor out you place a pressure gauge in the O2 sensor hole and start the car. At idle there should be not much over a half pound pressure ideally it should be no pressure at all: bring the RPM up slowly and the pressure gauge shouldn't go above 1 lb pressure. Anything more than that indicates a restriction in the exhaust. Usually a catalytic converter going bad. You could also smoke test the exhaust system to be sure it is completely sealed and letting no air into the cats.
Smoke testing the intake system would revel vacuum leaks that could be allowing unmetered air into the intake and fooling the PTCM. Watching live data on fuel trim might give an indication and being able to graph the O2 sensors with the scan tool makes it much easier than just seeing voltage numbers jumping back and forth.
Good Luck and please let us know if you find the source of your problem.