shift problem

i have a 1995 3.4l with 130,000 miles i just got for $250.
it sat for about 8 months not running. replaced the timing belt and power sterring pump. my problem is that it will not always shift out of gear when it needs to. it does this threw all gears too. example today it would not shift out of second gear till it hit about 4500rpms. sometimes if i let of the gas a little bit it will shift. any ideas on what this could be?

thanks for any help.

Check for code and see what you have. This could go either way, either there is a system problem (SES light), or you have a tranny problem.