I changed wires, cap and rotor about 2 months ago. Plugs maybe 2 year ago. Ran perfect till last week when I flushed the engines. Port engine idles around 700 RPM normally. But now it's around 1000/1100 RPM. Increasing the idle is smooth until you hit 1700 RPM. It then immediately increases to 2200 RPM.
I checked for vacuum leaks, there are none that I found. I checked the distributor cap and rotor. All looks good.
I installed the Rinda. Pictures below along with #7 plug. A hand is needed. Thanks.

Pics not loading on my phone (i’m in middle of gods country right now) but so you know, There’s a tsb or two on the distributor phasing for that engine. Slight different than the non cat 377’s too.

Does the iac work when commanded / tested with the scanner ?

I didn't check the iac. I replaced it . When it went bad it wouldn't idle. I could check it tomorrow. Had to stop due to cloud burst.