Assuming MAP and charge temp are reading correct, if the air per cyl estimate is smaller than you expect it should be then that generally means the engine is receiving more fuel mass than the ecu believes it is injecting based on the metrics it has been given to calculate fuel mass. - so the net effect is to get the air/fuel ratio correct you have had to tell the engine there is less air going in (ie you have smaller VE numbers in the fuel table than realistic).
There are many possibilities where that error is coming from, fuel density settings, stoich ratio setting, injector flow rate or dead times, fuel pressure etc. If the air mass estimated is reading half what you expect it suggests there is a fairly significant error coming from somewhere.
It would generally not cause too much of a tuning issue but some of the fuel model possibly wont work as well as it should if the estimates are a long way off.
If you attach a copy of the tune and short PC log I will take a look.
Add to that, if the value the ECU is thinking it's seeing from the rubbish old AEM sensor is different to what is on its own display, then the engine isn't actually running at the lambda it thinks it is.
I've just swapped one of these out on a car here for the exact same reason - the Link CAN Lambda was a breeze to install (I added the 22uF capacitor as per the alternative wiring diagram) and it's all substantially better now! I'm no longer fighting the readings on a daily basis!
