Not an authority, assuming the trans fluid is at proper level curious if the tran's has a ECT and/or OD; if so, does the problem continue with one or both in off or on position??? Also has the trans screen/fluid been changed recently???
Had similar problem w/ 90 T4r where trans started acting up and would not shift out of 1st gear until engine and trans warmed up. Decided to drop trans pan and replace screen, initially it did not solve the problem, however after I drove it several miles, I assume all the air pockets eventually were purged from the system and for the past several months trans has been working fine. I am not sure after 200 K mile mark the problem was due to dirty screen, or that I failed to keep proper fluid level and air got into the system??
When I pulled the pan I noticed several solenoids but since not familiar with transmission, or how to test trans circuits decided if changing screen and trans fluid did not work then likely have to take to shop. Anyhow, food for thought, perhaps more knowledgeable member will chime in with helpful info.