If your AEM has a narrowband output Try disconnecting the stock sensor and run the AEM narrowband output to the ECU. Wideband AFR's aren't "off the scale" until they hit about 22... A limitation of your wideband perhaps?
No, it's not your fuel filter or pump... You'd have MUCH bigger problems under a load than when you're at idle.
Part throttle boosting often involves the throttle still being open at a low enough angle that the ECU is still in closed loop operation and adjusting the fueling trying for 14.7:1. Check that this isn't the case. If it is then yeah, the cloud is probably extra fuel from the sudden surge when you finally stomp on it and the ECU goes into open loop.
You've tuned your fuel pressure while at idle with the vacuum disconnected? What pressure are you running presently?
I'd start looking for that noise in hardcore mode... Noise isn't good. Especially if you were running lean while booting and didn't catch it (been there, done that, replaced pistons).
What are all of the settings you're running now?
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