Hi, long time lurker with a problem that I just can't figure out
Bone stock 03 civic DX 130,000 miles

Within 1-2 minutes after start up on a cold engine, the idle will slowly drop to a point where the engine is just barely running. It will run like this for about 20-30 seconds and then the rpms come back up and it runs like nothing ever happened. It only happens occasionally but when it does, it's always within the first 2 minutes after startup as if it is on a timer. If I shut the car off while it's bogging down, it starts right back up and runs fine. There are no codes.

Things I have tried...
cleaned IAC valve and throttle body
checked pcv valve
checked for vacuum leaks
sea foam
plugs and fuel filter are new

Any ideas would be greatly appreciated!