For the first 20 minutes or so of driving my transmission acts like it is confused on which gear to be in. Constantly shifting from 3rd to 4th when I am at cruising speed. 50-60 mph. After about 20 minutes it will calm down and stay in 4th. It rarely ever shifts into overdrive and if it does it's only for a brief second. It pulls fine so I don't think the tranny is bad all though it does take a while to shift into the next gear from time to time especially when I am in the throttle. Taking up to almost 2 seconds and revving up to almost hit the rev limiter before finally shifting into the next gear. Do I need to replace or rebuild my tranny or could there be a simpler cheaper fix. I've seen some posts about maybe a throttle position sensor. Any thougts?

 

so what year - what trans ect - little hard to help you without information

 

Sorry about that. 2003 blazer 4.3L automatic transmission 4x4