98 C5 Vette Tranny Problems
 

I have an automatic tranny that seems to be slipping in Overdrive and slightly in 3rd gear. The transmission is a 4L60E with a 4L65 kit. This is my everyday driver.

Just had the tranny built less than a year ago by reputable trans shop in Missouri. Also installed a yanks nitrous converter with 3000 stall at rebuild.

Pushing 475 hp @ wheel N/A. I have not used nitrous since rebuild.
Any thoughts???