1996 s10 4.3l v6

I was on highway doing 75 with cruise on. All of sudden the truck downshifts and continued to do this while on highway but not surface streets. Is it tran auto relay switch or solenoid
(I have no leaking)
michaelmabe45@gmail.com
Thank you

Does your S-10 have a switch to turn off the cruise control? You may have bumped it or the switch may be defective. BTW…I would not post your email address here. Spammers are everywhere.

Post any fault codes you have, please
I strongly suspect you have a fault code relating to transmission operation.
You have the 4L60E transmission and there have been may technical service bulletins and updates over the years.
I may be able to help you if I get a little more info.
What is the condition of the fluid and filter.