It does not sound like the cat or the fuel filter would have any bearing on this.
A plugged fuel filter would cause problems when there is heavy fuel demand such as under heavy acceleration.
Also a plugged cat would be worse with high air flow through the engine. At idle, there is minimal air flow.
You might try putting the original PCV valve back on and seeing it it makes a difference.
A possibility is a vacuum leak of some sort, so that is why the wrong PCV valve is a possibility. Look for vacuum leaks in general. Look especially at all the vacuum lines.
It is probably a simple problem.
