I had a 70mm aftermarket TB with sensitivity... It was the return spring for the TB shaft, too big. More pressure on the pedal to get it open and then it would launch and light up the tires.
Went back to Explorer 65mm TB and swapped the swing arm from a Mustang TB, works great now.
96 Explorer motor, 70mm EGR spacer, 65mm 96 Explorer TB. 96 and early 97 Explorer motors have the same connectors for EGR and TPS as Mustang stuff