help X whistles idles weird

[93xltnewb]

93xlt

heres what happen i was at drivethrough
and all sudden i felt the car surge and i saw the voltmeter move a lil bit... i then started to hear a hissing frfom the engine i pulled over and opened the hood and it was evident it was hissing i tried to look for any plugs that got loose and i didnt find any
it seems like the hiss is coming from the driver side
and when im driving the truck is whistling and when ur about to stop at a stop light the truck would surge..

also when turning the truck off it seems like theres a 1-2 seconds lag for the engine to turn off
anyone help please
sorry about the long post
btw no check engine light goes on

 

[88vert]

Could be your idle IAC vavle

 

[93xltnewb]

iac valve is right by the airfilter.. the noise seems to b coming from the driver side it whistles when u give it gas
and when u are at parked and open the hood it sounds like theres a leak

 

[93xltnewb]

ok stupid question time
on the vaccum tree
i made sure all of them are tight
where do the other ends of the vaccum goes?

 

[93xltnewb]

i figured out what it was i think
i notice one plug missing on the vaccum tree
i didnt notice and loose hose hanging
so i just plugged it..
its the first one on passenger side facing the driver
infront of it was capped already
so i just figured to cap it.. anyone confirm this?