99 K3500 exhaust restriction?

[ken_man_1]

1999 GMC K3500 5.7L 70,000 miles 4x4

My question - I've got 4 codes coming up. P0131, P0137, P0151, P0157.

Upon inspection, I noticed that the muffler is starting to come apart at the back end, and it's startig to get a bit louder.

Basically I had trouble "all of a sudden" where I couldn't get the truck to go over 30mph and the engine would misfire and even backfire through the intake. I've seen what a plugged cat can do, and it seems the same here. However, this truck has 2 cats going into 1 muffler, then 1 pipe out. The exhause doesn't seem like freeflow coming from the tailpipe, and there isn't any hissing sound. It makes me think the muffler is plugged - has anyone seen this before?

[maxwedge]

I would disconnect the exhaust at the manifolds and see if it has normal power, that will tell you if this is an exhaust issue. Your codes are 02 sensor codes, make sure they are connected properly also.