1985 Chevy S-10

With it being manual start the truck and when it starts to whine push in the clutch if it goes away it's your throw out bearing for the clutch. When you say your truck is a v6 that leaves 2 options, the 2.8 or the 4.3. Honestly the 2.8 makes enough power to barely get out of its own way, on the other hand the 4.3 is a very strong motor. If you think it's your carb run some carb cleaner through the fuel system. I HIGHLY reccomend seafoam for an over the counter carb cleaner. It's not cheap at all but it does a GREAT job and it does exactly what it says it'll do.

Combination of your clutch and throwout bearing. Does it seem to shimmy a little when you have it in gear with the clutch depressed? Mine did that; took it to a transmission shop and they fixed it right up. Cost $800 but whatever.