Hello. I have a 1999 GMC Sierra with the 4.3. I have noticed that the transmission has started to shudder. Is there a fix other than replace the transmission? It does it only in 4th gear. It is the 4l60e trans. It has new fluid and I have tried Dr. trannys instant shudder fix. The engine also has a slight miss, could that effect the trans? Thanks for your time.