I'm new to the forum but have been a long time GMC truck owner.

My 1999 Sierra 1500 4 X 4 SLT Z71 with 135,000 miles on it doesn't want to shift gears when the temerature drops below freezing.

It will stay in 2nd for about a mile then shift t 3rd. After another couple of miles it will then shift to 4th and, again, after another mile or so shift into overdrive. After this it will then shift fine.

I've recently had the ATF drained and refilled with Dexron 3.

I'm hoping somebody can help me fix this minor issue as, apart from this problem, the [COLOR=blue! important][COLOR=blue! important]truck[/COLOR][/COLOR] looks and run great.