My 5.3 ls swap s10 does the same noise it sounds like a vacum leak but is not I have checked the 5.3 motor I have 0 codes for vacum leaks. And anothing that it does it idles high and the truck speeds up on its own but I findout is the throotle body u need to go back to a smaller or factory application I have the 102 mm throttle body and I notice that the hole where the idle air control goes to that hole on the 92 and higher throotle bodies the depth where the idle sensor goes in the depht is more reseed further than the factory throttle body!!! I had both throotle bodies and measured the depht and those aftermarket throotle bodys like the 92 and 102 mm are modified what happens is the idle air control opens and closes to a certain distance what happens when u have those throttle bodys install the holes depht is a bit deeper it creates a small gap allowing that extra air now the aide air control valve tries to close to maintain normal idle but what happens that small gap creates that sucking sound as the idles valve tries to close further it cant because it only opens to factory standards the idle valve fully closes thinking it has the factory throotle body if u dont beleive check the depht of both throotle bodies.
My 5.3 ls swap s10 does the same noise it sounds like a vacum leak but is not I have checked the 5.3 motor I have 0 codes for vacum leaks. And anothing that it does it idles high and the truck speeds up on its own but I findout is the throotle body u need to go back to a smaller or factory application I have the 102 mm throttle body and I notice that the hole where the idle air control goes to that hole on the 92 and higher throotle bodies the depth where the idle sensor goes in the depht is more reseed further than the factory throttle body!!! I had both throotle bodies and measured the depht and those aftermarket throotle bodys like the 92 and 102 mm are modified what happens is the idle air control opens and closes to a certain distance what happens when u have those throttle bodys install the holes depht is a bit deeper it creates a small gap allowing that extra air now the aide air control valve tries to close to maintain normal idle but what happens that small gap creates that sucking sound as the idles valve tries to close further it cant because it only opens to factory standards the idle valve fully closes thinking it has the factory throotle body if u dont beleive check the depht of both throotle bodies.
Nice! Im having trouble finding that intake!