First, check to make sure your kickdown cable isn't sticking. It wraps around the same pulley as the throttle cable and disappears into a black housing that snakes down toward the transmission. If it's stuck, it won't retract into its housing when the pulley is twisted. The cable on my '86 240 did this. Remove the cable from the pulley and hold the cable/housing vertical, then drip oil between the housing and cable until the cable moves freely. The problem will recur, but in my experience this will work for about a year.