Code P0894

Hi. Happy holydays!

i've had a dtc code p0894 (transmission component slipping). When the car is cold it takes about 30 minutes for the transmission to engage and sometimes it takes a several more minutes. Before the transmission engage I feel like a wave, like something unbalance (a wave move). I pressed the acceleration pedal and released on several occasions from normal idle speed to 2 thousand revolutions approximately. And loose it and feel the movement on the car in the shape of waves. When I do this I see on the instrument panel that it dials from first to second and up to third and then it goes back to first when I release it. I have to do this several times until the transmission applies(when it get hot). Already when hot, apply without any problem and run normal. I check transmission fluid level and it's ok, looks good, and does not smell of burnt. Check the transmission fluid carter and it looks normal for the age of the vehicle. I did not find metallic parts referring to excessive wear on the magnet. The solenoids were checked and are okay. What would be the next steps to follow? Grateful for the help you can give me and hope you understand my English and explanation.
Att. Juan marin