It sounds like its not locking in gear. If you take off the shifter bezel you will see what I am talking about. When you push the button in on the shifter handle it pulls a cable which in turn pulls a little metal strip. That metal strip locks the shifter handle in place on certain gears. If I understand you what you are saying is that you are putting it in drive, but when you pull away from a stop the shifter is moving into the next gear down, correct? If so, then it just isn't locking, because once you pull it back to drive, it should lock to keep it from going into second.
I would recommend checking the shifter handle. If the button isn't sticking out of the shifter all the way, then it may have been put in upside down. If this is whats wrong, then simply taking off the handle, rotate the button around, put it back on and test. | 
shifter drops down in to second gear 
or does the old trans do this i think its not right, if any one can help that would be great 
it was the nut that holds the shifter on the housing some how it came loose 
so it made my shifter loose and when i punch the gas it was droping in second gear. that should have a lock nut on it. Thanks for all the input 
