2009 Chrysler 300, 3.5 engine. (80,000 miles) Cylinder 3 missing. Receives P203 code.

When engine started from engine cold it will run without any issue. After car driven and it warms up and then shut off, and immediately restarted no issue. But if I wait even 5 minutes P203 returns.

If started from cold engine it can be driven for hours without P203 or missing cylinder. If I shut it off and restart 5 minutes later P203 returns.

Using nerd light verified pulse present at number 3 injector.

New coil pack connector #3

New pcm

New injector #3
new connector #3 injector

Coil pack on #3 swapped with #1

Replaced upper and lower gaskets on intake and plenum



Any ideas before the engine is removed or the car is traded in?? From what I understand engine needs removal for valve train work. Any help would be most appreciated.