transmission slipping at 1st start of the day
Automatic transmission slipping when engine cold symptom, pretty good chance there’s some serious transmission problems ahead. Ask your shop to make sure the transmission fluid is in good condition and at the correct level. If both are ok, you might buy some time by replacing the transmssion fluid with fresh stuff. New transmission fluid has fresh seal conditioners. If internal transmission seals are made pliable by the seal conditioners, that can allow the fluid pressure to build high enough to prevent the slipping symptom. For a while anyway.
Common sense says to also check for any engine or transmission diagnostic codes present. If there are some, you can post the numbers here for more ideas.
Have you checked the fluid level? Is there a delay shifting between reverse and drive?
While slipping doesn’t really describe this, it is normal for older Toyota’s to significantly hold low gears to help the engine warm up quickly. I have both an Avalon and T100 that do this for the first few shifts. It is very pronounced on the T100.
26 year old truck.
No mention of miles.
No mention of service history.
No mention of ownership length.
No mention of age of trans. 26 years old? 4 years old?