P CODES (POWERTRAIN) P0700 - P0799 P0768 Questions

I Own A 1998 Lexus Gs400. For About A Couple Weeks Now My Engine Light Has Come On And Off. Recently This Week It Has Stayed On Full Time...

Transmission Always In 3rd Gear . It Says Solenoid D , Replaced Solenoid And Wiring Harness . Still Stuck In 3rd

Code P0768 Shift Sol D. We Had A New Rebuilt Trans Put In 18 Months Algo, Now This Code If Coming Up @ 60mph It Is 2500 Rpm And When I Hit...