I have a 1971 Cutlass convertible with the stock 350 2V and TH350 trans. At full throttle from a stop, it accelerates like it should through 1st gear, then falls on it's face within 2 seconds after shifting into 2nd gear. It stalls if I don't let off the gas completely. Do you think this is a float adjusted too low, fuel filter (which was replaced less than 5K miles ago), or something else? It acts the same with or without the air cleaner on and the choke open, so I don't think it's a lack-of-air problem.

 

It could also be timing/dwell, spark plugs, etc... Does it sound like its missing?

 

Definitely sounds like it's running out of fuel but it is hard to say exactly why it is happening. As you said, it could be the float level is too low, a restriction in the fuel filter (is this the in-carb filter - paper or bronze? - or an inline filter?), fuel pump not supplying sufficient volume, hole in the fuel line allowing air in, etc.

 

Could be a worn rubber line at the tank or before the fuel pump sucking air also.

 

The car got a tune-up and converted from points to Pertronix when I bought it 3 years ago (maybe 2K miles ago?). Also, new fuel pump and in-carb filter around the same time. I don't remember if I replaced the spark plug wires or not, but I definitely replaced the cap/rotor. Also, no obvious misses.