HELP!!!LOUD whistle on drivers side of carb ...

...but hard to locate, even with a stethoscope.
truck died suddenly on acceleration and had to have it towed. started up the next day and gave a code 35. any ideas?
1993 chevy s-10 4.3
new to forum.
thanks!

Carb? Was the engine replaced?

The '93 4.3 will either be TBI or CPI. If it's TBI, you probably need to replace the TBI gasket as they will eventually fail and cause a vacuum leak - the whistle.

Code 35 is IAC system.

thanks for the reply,
this is my friends truck. he replaced the gasket. it whistled for a few days before it quit ...kept on doing it after he changed it.
any other ideas?
thanks again

PS-when it died on him he had it towed to his mechanics place. the guy couldnt get it in today so we drove over there and checked it out. it started right up so he drove it home. we checked the codes and got 35 and then disconnected the battery to reset. the code hasnt come back yet but it was only a 5 mile ride. it still whistles really loud at idle and goes away when accelerates hard.
what ecactly is the idle air control ?