Got a 73 C10, 350/TH350 and the problem is it is shifting
way too fast. After I go about 30 feet, it is already in high
gear and will not drop to a lower gear unless I push the pedal
all the way to the floor. When going up a hill it will remain in
high gear and the motor labors so bad it almost stalls unless I again push it to the floor. Could the modulator be bad or is there something else I can look for before I take it to a shop or just change it out for another one.