I have never owned a car with throttle body EFI, so I didn't realize there was an idle stop screw like a carb.
The Howell setup looked very nicely installed so I **presumed** that whoever installed it knew what they were doing.
But, the PO had all the vacuum hoses wrong. Namely he had the PCV port on the throttle body connected to the intake manifold instead of the PCV valve and purge canister. In order to make get enough air to idle he had to open the throttle butterflies which closed off the ported vacuum.
And, you can't just adjust the screw to set the idle. There is a whole setup operation involving resetting the EFI brain which I need to do once I get the time.
1974 J20 Pioneer, ZZ/8,000 GVW, 401-4V, QT.