Accord 87 Auto early shifting

[junooni]

My Accord 87 shifts up at around 2500rpm and 3800rpm with kickdown.....

As a result, the pickup is pathetic.

Also, the shift-up from 2nd to 3rd 'slips' (engine revs up high with the shift stuck in the middle, and then the car shifts up)

I have changed the oil and filter and the oil level is also ok.

I've changed the tranny (used actually) and a local mechanic has installed it so i'm thinking maybe there's some cable setting or anything that i can do?