please help, my brother-in-law did some work on my parents truck, took off carb and intake manifold to clean it. put it back and now it doesn't shift gears while driving. it's an auto. engine idles good but when in drive, it's quite low. could it be a vacuum issue only? what is involved to have a trans shift gears?

 

You did not hook up the downshift cable that gives the transmission throttle position information.
You may have missed something more as well. Get a downloadable copy of the manual to check the repair against.

 

awesome, thanks skypilot, this gives me a good place to start.