plugged cat converter

[LeeRoy]

My friends GMC Sonoma started running poorly. Cat converter was observed to be nearly completely obstructed. I asked him what kind of air filter? Innocently. He says K&N. I says maybe your problem. He became mildly irate. Less than 50,000 miles from new. Was I out of line? Seems to me possible cause/effect relationship.

 

[vad]

Possibly.
Oil contaminated MAFS --> screwed up fuel/air ratio --> overheating cat converter --> cat failure.