Engine running rough?

If the converter was replaced, double check the pipes and muffler, it sounds like a piece of the old converter bed is wedged inside one of them, this will not allow the engine to breath and the effect will be your symptoms.
Attach a vacuum gauge to an intake port, raise idle to 2000 rpm, hold rpm steady, if the vacuum gauge starts to drop, the exhaust is clogged. Or go to Autozone and get an exhaust system backpressure tester, remove an O2 sensor and screw the tester in, start engine, pressure should not go higher then 2 psi

Sure, let me know how it goes, TEST first! Replace after testing!

Hi wow, well the oil pump is not likely causeing the eng to run rough. They need to check compression
check fireing order
check vacum routing
check vacum
check cat convertors, possibly water in them
scan the vehicle.
However after head gaskets are installed it is nessacary to run car a few hundred miles to seal gaskets. Taurus will normally run a little rough for this period. Billymac