My 75 280z had similar symptoms. The plugs would get flooded and the engine would shut off. When I drive it, the engine would choke and run like crap. It would not rev pass 3000 rpm.
I just fixed it the other week. I will ask my father about what he did specifically. I remember him say that it was a problem with a GROUND connection. When he grounded the connection, the engine would idle smooth. When he removed the ground, the engine started to choke again. The car ran perfect after we fixed the GROUND connection. Right now though, the car is not running do to a bad voltage regulator.