My 1999 1.8 20 valve turbo was running like crap, so I did a scan and got three codes. p0422 p0303 p0301. I cleared all the codes an replaced the spark plugs. Drove the car for about 250
miles to cycle the OBD codes. The car runs great now but the P0422 code came back in the Pending codes. I was told that it might be a bad cat so I removed it and inside it is off white color and all of the pathways look clear. The front oxygen sensor was the same color but the back was gray with some large black spots on it. The engine code is (A). Is a visual inspection good to determine its condition or is it a chemical thing. This is the original
cat and I don't want to replace it if I don't have to. If it's not the cat then doe's anybody know what else it might be?

 

missfire codes?
the cat will need some time to recover if it wasnt ran to long with the miss
coils go bad too