I came across the Vessel (Bessel) Impacta 980 series of screwdrivers on Amazon. They work like regular screwdrivers normally, but act as impact drivers when hit with a hammer.
Here's a terrible photo of the 150mm P2 making contact with the lower IAC screw, without removing anything. The angle isn't ideal, but it's good enough to loosen the screw cleanly:
My prior method was a Dewalt impact driver with a 1/4" long hex bit and a 1/4 driver extension, but that required removal of the PCV hose. The impact driver allows you to focus on leaning into the screw so that it doesn't strip:
The 150mm P2 size is currently $11.82 on Amazon:
Vessel Megadora 980 Impacta P2x150 #2 JIS Cross Point Impact Screwdriver - Phillips Head Screwdrivers - Amazon.com
Information on the Vessel English website:
Megadora : 980 Series
Here's a terrible photo of the 150mm P2 making contact with the lower IAC screw, without removing anything. The angle isn't ideal, but it's good enough to loosen the screw cleanly:
My prior method was a Dewalt impact driver with a 1/4" long hex bit and a 1/4 driver extension, but that required removal of the PCV hose. The impact driver allows you to focus on leaning into the screw so that it doesn't strip:
The 150mm P2 size is currently $11.82 on Amazon:
Vessel Megadora 980 Impacta P2x150 #2 JIS Cross Point Impact Screwdriver - Phillips Head Screwdrivers - Amazon.com
Information on the Vessel English website:
Megadora : 980 Series