Had same problem while on vacation, so I took to a muffler shop and paid $400 for a cat and that did not fix car. I drove home in the same condition as before ( Red hot Cat and no power, was getting 8 MPG LOL) eventualy got my mechanic to take a look and it was the coil packs and only $130 so I wasted $400 on replacing cat.
I know this is late but thought it might help someone else