When taking off my trans shifts from 3rd to 4th while giving steady gas to truck.
As i reach my crusing speed say around 45mph and i let off the gas it down shift to 3rd for a sec then back into 4th. Local tranny shop says my trans need major
overhaul $2500. I dont think so acts like sticking shift valve in the trans of faulty TPS but i am not sure any help will be great appericated.

 

Those were the initial symptoms we experienced with our 4runner. Faulty speed sensor. Of course, the ecm and a few other things got fried when lightening struck the thing in our driveway. Once that was confirmed, insurance covered the repairs. So far so good for 14 months or so.