URGENT Please Help! 4R55E Torque Converter Question

[PhdNPrerunners]

I have a 96 4.0 with a 4R55e that was rebuilt 20k miles ago (out of warranty previous owner was an old man who passed away so the truck sat for a while). Lately on the freeway my truck will shift into overdrive fine which the rpms are at about 2000rpms at 65mph and then all of a sudden it will be seem to down shift but not into 3rd. The rpms jump up to 2400 and stay there but if I hit the overdrive button and cruise in 3rd for a min or two it will shift back into od fine once I hit the button again. Does this sound like the torque converter is going bad? I have no flashing od lights or check engine lights. I need all the help I can get cause I am driving it 1800 miles to California for school in 2 months. Thanks guys

 

[PopRichie77]

Sorry but from your description, I can't tell if the TC is unlocking or if it is shifting to 3rd gear with the TC locked. You could have a bad brake pedal switch which will unlock the TC. A normally operating switch will unlock the TC with just a slight tap.

 

[PhdNPrerunners]

It will shift into od but seems to unlock randomly but doesn't go into 3rd when it does unlock. It stays between 3rd and od

 

[PhdNPrerunners]

Anyone have an idea as to what would cause the TC to keep unlocking in OD?