My transmission will kick down a gear without me putting my foot through the pedal. I don't engage the tranny kickdown. I have checked and reset the modulator valve, nothing helps. It will kick down a gear for a split second then shift back up, like it's mini stalling. I've checked everything on the motor, carb, and etc. I was told by an Oreilly's parts salesman that it is probably the secondary governor.

 

If you have a restricted line anywhere it causes vacuum to be depleted for a split second and that can cause it.

On some trucks the primary governor weight is a great big honking **** and the secondary has an extra plug installed.

The valves can be installed from a different governor or the entire assembly can be changed.

 

where are all the vacuum lines running to the transmission? I know of the modulator one.

 

By vacuum lines I mean all vacuum lines, not just to the transmission.

 

the only vacuum lines I have hooked up are: the modulator line, the power brakes, and one for distributor advance.