1993 Voyager rebuilt transmission problem

I have a 1993 VOyager with the a670 transmission.It was just rebuilt and a new torque converter was also put in.It will not shift out of first gear 90 percent of the time.I dont know what to do.I seen where ppl were attaching hte gov. spring kit with not change.Is there any other things I should look for.THis is my only vehicle and I need help really bad.Any suggestions would be appreciated.Can I check for error codes?COuld it be the speed censer?