I just got my mack daddy, full billet Dtt auto professionally installed in my 2003 HO dually 4x4. My brother and I installed the volt regulator and the noise filter and now the dang thing is stuck in third. Sometimes it will down shift to first if you put it there manually sometimes it wont. It will not downshift or upshift on its own. I am fairly certain that the filter and volt reg. were installed properly. Any suggestions?? Thanks in advance.