[fortythirtyfive]

Slight update to this seen as the thread appears to be getting a lot of views as of recent.

A few weeks ago I installed the B58tu HPFP and flashed MHD's stage 2 hpfp map, since then the stumbling has vanished, every cold start is crisp and spot on. At first I thought maybe it was my fuel pump going or perhaps parameters being fresh from the flash, so I flashed back to stage 2+ multi-map and within the next 2 cold starts the little stumble was back.

I flashed back to the stage 2 hpfp map and bam, 4 perfect cold starts back to back. So maybe there was a mixture of fuel pump upgrades at play, but it does seem like cold start idles aren't perfectly ironed out in their 2+ maps.