The plane had an STC for auto fuel. The FAA thought carb ice but of course, no evidence of that. The rest of us thought winter grade auto fuel on a warm spring day = vapor lock in the carb. Either way, carb heat did not clear it up. It sputtered and idled but any throttle and it fell on its face. I was about 2000' AGL when it first went "burp". It went right on running after that first falter, but I was already heading for the closest known airport. It was not long before it alternated with bouts of thrust followed by relative silence. I ended up at 1000' AGL with nothing but bad choices ahead, and the descent up to that point left no doubt that I would not make that airport.
Maoraigh1, I call anything pattern altitude or above, "at altitude". That poor guy in the bulldog was probably in the 200 AGL and maybe a few degrees left or right of straight ahead sort of thing.