FIG. 1 is a perspective top view of a carburetor throttle body showing my new design. FIG. 2 is a left side elevation thereof. FIG. 3 is a front elevation thereof. FIG. 4 is a rear elevation thereof. FIG. 5 is a right side elevation thereof. FIG. 6 is a top view thereof; and, FIG. 7 is a bottom, plan view thereof. The broken lines shown throughout the drawing are for illustrative purposes only and form no part of the claimed design.