How did you clean your intake valves ? Walnut blast?
When you say "stumbles", might you be describing "Low speed pre-ignition ?
(LSPI) is a premature combustion event, occurring prior to spark ignition
it occurs when engines operate at low speeds and high loads.
It can result in extremely high cylinder-pressures and can lead to heavy knock
You said fuel trims get better when you disconnect the clean side PCV breather hose from the air intake plenum
Did you also say .. the "stumbles" go away when you disconnect the clean side PCV breather hose from the air intake plenum?
And... regarding fuel trims ...
Did you drill out your dirty side PCV orifice?
Did you drill the fixed dirty side PCV orifice top hole to 1/8" and the 2 bottom holes to 5/64 ?
2012 Tracerse AWD (80k miles) with Elite E2 X catch can
Three Equinox AWD, 2013, 2016, and 2016 (all are 2.4 liter, 4 cylinder engines)
2017 Equinox AWD, 6 cylinder engine, with Elite E2 X catch can