automatic transmission problem in 2003 S-10

Tansmission seems to slip sometimes going from first into second and when it down shifts also when going up hill. Kind of hard to discribe what it is doing.

Auto transmission?
Fluid level and fluid condition?
What is the mileage and service history on transmission?
Is the engine running up to par?
Any codes or check engine lights?
Remember the engine has to be running good for the transmission to work good.
On a normal take off at what MPH are the up shifts?
1-2 2-3 3-4 and lockup?

new transmission fluid and full, only 34,000 on truck, truck shifts normally on a level grade, good quality fluid and filter

new transmission fluid and full, only 34,000 on truck, truck shifts normally on a level grade, good quality fluid and filter

Get it on a good transmission and engine capable scanner and read out data and past and present codes.
Watch the shift adaptive reading for a slow shift.
Mt