Smoke / Vapor From Oil Cap?

It's normal for a well worn engine..

That's normal for a worn in engine....but that breather is a no go. Its causing the reading to be off for the MAF sensor. The tube on the filler neck runs to the throttle body. Hiring the gas causes a vacuum on that hose so it can reburn the vapor. Right now it will suck fresh air through that breather and pull fresh air into the throttle body. Ford had a cap on there to keep that from happening.

At idle the PCV valve should be pulling a bunch of that vapor into the intake. Check your PCV valve in the lower intake between intake and firewall. Check the screen below it too. If its clogged it can cause exactly what your car is doing.

Get rid of that breather.