Butyric acid/vomit smell

So now that the weather has warmed up, my 66 Newport has acquired a mild smell of butyric acid (vomit) when it sits in the sun for a length of time. Not present when it’s cool or cold.

I’ve had the entire interior out, steam cleaned absolutely everything, and the only thing I can think of is perhaps there is some component of the dash pad that out-gasses in the heat and has this terrible smell.

Is it just me or has anyone else experienced this?
Author: darth_linux