Does anyone know which episode had a patient who wanted one of the docs to cut off his foot? I think in the end he found a saw and started to do it. Thanks!

I'm pretty sure that that was an episode of Grey's Anatomy. In fact I know that it happened on Grey's Anatomy. I just don't know whether it ever happened on ER.
Was it a halloween episode with a labu carving contest? A chainsaw? Possibly the actor was Rocky Carroll?
I would guess that it was season 4. In which case it might have been Haunt anda Every Day
This also happened on Chicago Med with an arm although the patient didn't cut it off himself.

that was an episode of Gray's Anatomy on ABC. The man comes into Dr. Bailey's clinic complaining his foot isn't his, on the same hari of an annual chainsaw carving art contest. While Bailey is looking for Psych help for him, he makes off with an injured Artist's chainsaw and nearly amputates his foot, blood flying everywhere. Dr. Callie Torres completes the amputation.