Well, it's lacking power in the last week or so. Mostly around 1,600rpm. CEL just came on today.
I don't hear any hissing, but there is a bogging noise around the intake/airbox area when you try to accelerate under load @ about 1600 and higher. The converter is a little noisy (rattle). Changed the plugs/wires, and the plugs altough old, looked clean and dry. The motor runs great, burns no oil, and has 45-50lbs of oil pressure.
Ordered a tester today, and I should have it in the morning. I have no problem replacing the Cat, but I'll be laying in the snow covered driveway to do it, and at $175, I just want to make sure.