Re: throttle body
i can tell you that some times the actual shaft gets dry and dusty and will cause a sticky condition which usually only occurs when you eas off the throttle and then if you burp the throttle it closes fine.
the other thing i have seen is where the throttle cable is held there is a plastic sheath type piece that slides inside another plastic piece and i have seen them develope a small catch on those which will stick periodically.
if that is the case you have to trim back that plastic just a smidge.
i would rather push my Ford than drive your Chevy !