I was just wondering, what are you feeding him? The Karo is great to bring them around in an emergency, but it has this funny effect of spiking their blood sugar, leading to a drop
Here's a link to the formula given to me by a breeder with 30 years experience that saved my Luna's life. I only had to force feed her once or twice, and she started pigging out

Pups need good carbs plus protein to keep their blood sugar stable, and this does the trick
http://www.yorkietalk.com/forums/showthread.php?t=58036
I pray that your darling baby is better soon