Problems shifting out of 1st when cold
My '97 D-90 automatic tranny is having trouble shifting out of first gear afte a cold start (mornings etc.) Seems to run up to about 3,500 - 4,000 before it even thinks about shifting. After it has warmed up it shifts fine. Thinking that it may be a viscocity issue (cold no flow, warm good flow) I had a new transmission filter kit installed. This made it mildly better, but I am still concerned about the high rpm shifting in the morning.
Any help or suggestions is appreciated.