I was thinking more of excessive blow by past the rings. Sooo - is it blowing or sucking? Either way check the PCV valve if you haven't already.
Another thing you can try is disconnecting the wiring harness from the EVAP purge solenoid. That'll rule out a leak in the evap canister or lines to it.
Did you see my thread on P0171 -
In the video I'm using carb cleaner but earlier used CRC MAF Sensor Cleaner. The CRC actually seemed to work better, it affected the idle while being farther away from the leak than the carb cleaner. Both are flammable so you should really have a fire extinguisher handy.