Acceleration and power problem

Something happened to my post, What I wrote has been deleted and an other threads post took its place!

Don´t have time to write new post right now... will be back.
//F

OK a new try:

Bad acceleration and can't keep up speed uphill. Doing 80km/h (on flat highway) and then presses the accelerator to the floor. Transmission shifts down and engine revs to 4000 but no acceleration! Does not shift up until the acc. is released. With a more gentle press on the acc. it accelerates slowly.
There is a whining noise when in drive or reverse but not in park or neutral, possibly torque converter(?)
After doing this kickdown thing the SESlight comes on with a O2 code, and it goes off after some time "normal" driving...

All this started after a tune up at the shop, they did change plugs, air and fuel filters, engine oil, ATF in tranny, oils in diffs and transfer case.
They told me the O2 sensor probably was the cause of the problems so they put in a new, but it did no good.

My question is: Is this a tranny problem or a engine problem?

ATF level in tranny is OK.
Have not checked fuel pressure due to lack of manometer...

What do you think?

/F