When engines are replaced, the wrong accelerator rod is often used. They can be bent/welded/modified to work.
Have someone depress the gas pedal while you look at the hole in the floor where the accelerator rod comes through. As the pedal is depressed there should not be excessive up and down movement of the rod at the hole. If there is, you will need to bend the rod until there isn't. A rod which does not travel freely through the hole will cause your issue. Since there is a bell crank involved, this effect is multiplied.
Carl
