For transmission issue the most common is the linear solenoids getting stuck. on YouTube search for “re5f22a transmission the symptom the repair” by Hiram Gutierrez. It explains in great detail how the solenoids are fixed. Your mechanic may or may not have the tool to pry them open so show him the vid when u talk to him. If he has a good scan tool like the maxidas that Hiram uses he can check the transmission code first. Solenoid job should be much less than a thousand bux. Doesn’t sound like its slipping so the clutches and hard parts are probably ok that’s why I’m leaning toward the solenoids.