Startup rattle only when hot

[radroach]

So had this issue for a few years now. I think the first time I noticed any problem was after valve spring recall, about 5 years ago, in summer with 100*F hot grocery store packing lot, started car up and it rattled bad on startup, but went away with a couple revs. Car drives very good otherwise the last 35k miles. Startup rattle has been happening frequently starting last couple months so deciding to make a post about it.

Startup rattle is most apparent when warm or hot and the car is sitting in direct sun. Cold starts in the morning or in shade, no problem or is much less of an issue. Any rattle always goes away with a pump of the gas pedal.

I think that fueling is suspect. Somethings not calibrated right on startup. Oiling or timing chain probably my second suspect but much less so because morning cold starts are good.

Since I don't have a tuning solution, I'm thinking of just pulling the battery and resetting systems, do you think it could change startup fuel trims and perhaps make them a bit richer?