How will I know if I have bad Cadillac convertor or bad fuel filtet

Assuming your check engine light is not on, which would provide codes to point to specific issues, check these areas: air and fuel filters, spark plugs and wires, transmission fluid and function. If filters are clogged, improper fuel mix and hesitation could result, if plugs are fouled or improperly adjusted/cracked, giving a weak or no spark, and if transmission fluid is low, burned, incorrect type, coolant intrusion or tranny worn, that would allow excessive slip. Check that brakes are not dragging, or parking brake needs adjustment. It is unlikely catalytic converter is culprit unless engine is very worn, burning oil for example. BTW, did changing the sensor make symptoms worse?