what would make the car feel like it slips going from 2nd to 3rd but other shifts are fine

here is the problem car shifts fine from 1st to 2nd but acts if though it is slipping going from 2nd to 3rd it does this for a few weeks then it has stopped for about a week started doing it again today have been told its the transmission but if memory serves me right transmission problems don't stop and start e mass air flow have had a scan ran by a mechanic friend we found no codes fuel pump has been replaced as well as filter here is the crazy part i did use the cruise control today i read on another site someone else was having a similar problem come to find out it was the cruise control switch is this possible it is driving me mad thanks for you help