Ram air air cleaner breather

Sounds like a PVC /breather issue. Ran the same K&N breather you have,had the same problem. The best breather I have found: Stock Chrysler. Order one,for a 78 Cordoba 360/400.Do you actually run a PCV valve? These might help your situation. It's cheap,(10-15 bucks) and may solve the problem. Ran into exactly the same situation on two Chevies.