Converter lock up too soon?

[jhngardner367]

It may not have the 700r4 trans.
Does the shift indicator have a "D",with a circle around it,and another "D",then 2,then 1? If not it is probably(as in my '85) a 350c trans.
These trans.,have a vacuum-actuated switch,usually located (looking from front of truck) in the upper left cowl area. It closes the solenoid,in the trans,to lock up the converter clutch to provide a direct fluid coupling( 1 to 1 drive).
When the brake is used,during stopping/slowing,it disconnects the solenoid,to allow the vehicle to idle without stalling.
Mine locks in at about 35mph.
The "bog" you feel,is the converter locking in,and is normal.