I have had hesitation and what felt like momentary clutch slippage for months that mechanics cannot figure out. Recenty a mechanic replace the plug wires and this improved it but did not solve it. It does not "slip" or "skip" anymore, just hesitates at low to mid RPM's. If finally threw a CEL so I took it to Autozone and they pulled two codes. Engine miss and O2 sensor. The book that came with the code reader said when these are read together, it means the cats are plugged. It makes plenty of power at high RPM's. Does this make sense? What should I do next? I have little faith in mechanics to figure it out. I don't mind putting O2 sensors on it, but new cats are very expensive and I don't think it's worth it. I'll just leave it how it is if they're plugged till it won't run anymore. Thanks for the help.

Oh, I forgot to mention, it has 156K miles but I replaced a hydrolocked engine at 131K. Original exhaust, of course.