Delayed acceleration and sputtering

My New Yorker does not respond very well when I press the gas pedal. It will either delay, or it will die. It seems to spit and sputter a bit. It does this primarily when coming out of a stop light or sign, or slowing down, or being idle for a couple seconds. It has a hard time speeding up when I am getting on the freeway, and feels like it's working hard as if trying to get more fuel for it to go. I feel like a danger (and annoyance) to those behind me because I have to take it easy and slow, and on hills, it goes very slow or it dies. I took it to an auto shop and they said they couldn't scan it because the check engine light is not on. What could it be? We've replaced the air filter, fuel filter, plugs and wires, cleaned the carb. Please let me know what I could do!