Please help !  I'm experiencing exhaust problems..................

Two weeks ago my van was running great, but blew a hole in the elbow pipe that connects to the cat.  I replaced the pipe, and have since had a hard-to-notice loss of power.

I then suspected the catalytic converter and disassembled one side of the pipe to take a look, however I eliminated this as a cause b/c the catalytic converter seems to have been hollowed out by time or the P.O.

But now.... after re-assembling my exhaust I now have black smoke coming out the back and it's driving "funny" !!

Is it possible my muffler is bad?  Or maybe something more serious?  All help appreciated because we're leaving for holidays on Friday.

Thanks,
Shawn.

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