Did you solve the issue?
My 2016 cruze limited 1.8 6MT has similar issue especially when the ambient temperature is 60F or below. Sometimes, the car just stalls itself when it is below 50F outside. Got P0171 code.
Check my PCV. Sprayed a good amount of brake cleaner on it, and the idle speed wasn't affected.
Changed downstream oxygen sensor due to reported codes more than 3 times and found out an ebay unbranded oxygen sensor was installed. Changed it to Bosch(OEM) and still got rough idle and P0171.
I am clueless now...