Removal Of Catalytic Converter

The Cat had broken up on my 1992 200TE Wagon. I thought it may be causing my problem with the car hestitating on acceleration (intermittent throttle delay) but it wasn't the problem. My mechanic said that i don;t need a new Cat on my 1992 car so he cleaned it out. It then gave a bad rattle and resonance noise so he removed it completely and replaced with straight pipe.

Somebody asked me to check the O2 sensor to see if it was causing the hesitation issue. Is that likely to still be on my car or would it have been removed along with the cat?