It sounds like my Convertor is starting to get plugged

 

1) Catalytic not Cadillac. 2) I've driven a LOT of vehicles well past 200,000 miles, one went to 408,000 and I never had a convertor plug up. What makes you think it is plugging up?

 

In 1986 I bought a 1982 CJ7 that was traded in at the dealership I was working at. We used to run the sand in Mexico a lot back then and horsepower came in really handy. In the earl 90s sometime I installed a TPI 350 and a turbo 350, solved the running in sand issue quite well. It used to set idle a lot and in the early 2000s it started to become very sluggish and was running hotter. Took it to a friend who owned an independent shop told him the symptoms and added it was like the cat was plugged. He suggested an injector flush and with no improvement he wanted to replace the injectors. That motor had 9 injectors and @ $200 each I said pass. Took it to another shop, told him about the symptoms, said it was like a plugged cat, they took the cat out and it ran great. So they do come apart inside and get plugged. I had to put on a new one, they check in AZ during emissions. Sorry about the length.

 

Right front cat from our SRT6 was broken inside, and then plugged. It may depend on type of car. Turbocharged engines are notoriously hard on catalysts, and between the exhaust gas temperatures, and the full rich conditions that most turbo engines will exhibit at wide open throttle, melted and plugged substrates become the norm. On more pedestrian vehicles, so long as you care for them, and don't continuously beat the snot out of them, the catalysts will keep from plugging for a long time. Their efficacy does drop at about the 100k mark, or so, hence the way emissions warranties run out....

 

When I start up and go its fine for a minute. Then it starts getting sluggish and sputter. If I go at a high rate of speed it doesn't do it. At the light while I'm idling it runs rough.

 

What readings do you get from the O2 sensors?
I have had similar symptoms with a failing fuel pump, from a cold start the rich mixture was fine but when it warmed up the leaner mixture was not rich enough to keep the engine smooth. I do not think it would run smother at higher speeds though. The fuel pressure was under 10 psi.