Assuming your valve body isn't malfunctioning, you can adjust shift points with the kickdown rod. It's connected to the throttle linkage. Follow it down to the transmission. When you get down there you'll see the adjuster. Go one way and the shifts come sooner. Go the other way and they stretch out. Adjust to your liking.Now, on getting to 4th gear with a 3 speed transmission? Can't help you there. That's a keeper!