I don't know if it could be the vacuum lines. I wish there was only one like the older models. But my friend and I hooked them up based on another Fiesta owner's format. We used a PCV valve and made sure they were properly connected.Are the issues still relating back to the vacuum line issue? If you haven't gotten that sorted, it could lead to your current challenges.
Some exhaust info on hereI'm curious as to what options are still available for a 2015 1.6L SE since it seems like SE parts keep getting discontinued.
Wondering how much the 1.6L SE has in common with the ST in terms of exhaust, since if this is anything to go by...:
My hope is the aftermarket will be just as flexible.