Most likely the kick-down adjustment is too tight.
On the throttle lever at the kick-down rod attachment, you will see an adjustment screw. open the throttle with your hand and you will see where the screw hits the kick-down. Back it off some and take it for a ride. Adjust as you go (pull over) until you get it where it feels good to you.
Below is a photo (disregard high-lite) of a 4300 MOTORCRAFT carb. Do you see the large lever with a large adjusting screw and the attaching kick-down rod (this attaches to the lever on the side of the trans main case).