Did you check the OBD2 for a pending CEL code? Even though the wrench is gone, a pending code could be registered while not throwing a CEL yet. Just trying to help.
I have used catch cans on my prior supercharged & modified Mustangs. For my 2018 I4, i chose to leave the car bone stock. This would elude to not using a catch can. Its still about preference. A catch can is an after market modification as we all are aware. My modified cars were not serviced by...
Most people who own Mustangs are OCD about them . Its just part of owning a world renowned sport car, that's been around for over 50 years.Enjoy & have fun with the ride. :cheers: