1992 Toyota Camry Late final overdrive shift in cold weathe

Transmission will not shift into final overdrive shift until engine is thoroughly warmed up. Temperature below 40 degrees F triggers problem. After shifting into final overdrive shift, it will shift back out when engine temperature has decreased during highway driving then shift back into overdrive after about 5 minutes. Transmision flushed in summer of 2008. No engine trouble lights or transmission overdrive trouble lights.