Rough idling acceleration issue foul exhaust smell bad fuel economy?

It rough idles from 1k to like 400 and it has accelerating issue. When I press the gas revs go up but not the speed. There is just a random shift when I push the gas 75 percent down and it starts to pick up. We changed almost everything beside the fuel pump and fuel injectors, we had a valve leak but fixed it and there is a foul rotten egg smell. We thought it was the Catalytic Converter, so we took it off and there was no increase in performance. We thought maybe it was clogged but didn’t seem to change anything but the sound. So, we put it back on and we tried to decaf on the engine with some foam but didn’t do anything either. we tried doing it with some brushes, but it didn’t change anything either. Also, bad fuel economy; I drove 2 miles and it took 7. Just confused on what’s the deal here. al