This is the flexible tube that starts at the very back of the chassis (where the accelerator cable comes out of the center tunnel) and goes up to the back of the engine fan shroud. It connects to another tube that runs through the fan shroud. It protects the accelerator cable from dirt, debris and heat. It has some spring to it and does assist the accelerator cable in functioning properly.
Anytime you replace an engine or even an accelerator cable, it is a good idea to replace this item. It is sometimes called the accelerator bowden tube. This tube measures 598mm or 23.5" Long.
EMPI