I have a scan tool. I will try that this weekend.Do your best to count the number of upshifts next time you take it out for a drive on the freeway. Wrong gear starts isn't converter. Its usually valve body and occasionally shift solenoids but sometimes can be something inside the case (not nearly as likely, however).
Better yet, if you have a scan tool that will display transmission live data you can immediately rule in or out a wrong gear start. Any Snap on and most Bosch or Autel scanners will work as will an MDI subscription from AC Delco diagnostics for your vehicle ...