is sluggish and won't shift to lower gear, seems to be staying in Drive mode

What is your question?

Very slow off the start once up to speed seems to work ok, it seems like the transmission is not gearing down, I tried putting it in low gear and it seemed to stay in the D mode.

What makes this problem better or worse?

Car temp does not seem to make a difference

How long has your 2008 Nissan Xterra had this problem?

a few days