2003 3500 6.6 Duramax w/Ally. 47K miles. Stock truck. Under no load, backed up from my parking spot, put it in drive and I think the tranny limped. CEL on, pulled up code 700 and 734. 4th gear ratio incorrect. Fluid changed by dealer per manual. Next one was due at 50k. Cleared codes and truck seems to shift fine. Dealer says that these transmission modules "act up" sometimes. Any thoughts?

I was getting on an interstate once and accellerating pretty hard but not that hard. Hit 4th gear and stuck. Not limped cause the revs stayed high. Would not down shift or upshift. Got off and drove it home and all the way it would'nt down shift or up shift. Engine light came on. Scanned and cleared 2 codes with my Superchip tuner. "Stuck solenoids". Restarted the truck engine light out and shifted perfect. Has'nt done anything abnormal since. (2000miles since) I did change my spin on filter as I had not done it since truck was new. I had about 10,000 miles on the truck at the time.