Actually, the PCV system gums up the intake more than the EGR system does.
High combustion temperatures create the NOX gas...which is part of the "cause" of acid rain if you will.
If you run less AFR, while being less efficient.....it uses less fuel. That's why removing the EGR system causes your economy to drop...you're getting more clean air into the engine...so you can use more fuel to increase the HP.