I have a 2000 Blazer 4x4. Hard shifts in to OD and it seems to drop out of OD a little to easily. A slight acceleration makes it drop down then at times it will jump right back into OD and it does it hard. Also, when I accelerate from a dead stop it sometimes seems to be a delay for it to into 1st and start pulling (very intermittent).

All this seems to only happen once it warms to normal operating temperature.

 

Driving through some mountains today I dropped the the shifter down to 3rd. I had the same hard shift problem between 2nd and 3rd. Anybody have any thoughts?

 

Have you changed the transmission fluid & filter recently? Should be done every 36K, especially if you're in the mountains frequently.