I just bought the car with a bad motor(broken valve) an put a used engine/tranny in it an it runs great but for the first half of the throttle it does very little then at around 50% of the pedal its almost wide open.... to an extent it drives like it has a stall converter but is fully stock. There is sort of like a "sweet spot" like a clutch where the pedel gets sstiffer n as soon as u hit it it tosses ya back in the seat. (Alrdy did new throttle cable and made sure the throttle body wasnt getting stuck. But there's no in between its all or nothing. Anyone every had this happen?

 

It does sound like the throttle position sensor is defective.