Hmmm strange.
If its only popping and stumbling on startup then its unlikely to be DI seal problem.
If its popping out of intake when warm then that's an indication of DI Seal issues.
Check out your LTFT if their greater than 10% then you likely have exhaust or intake leak or some other issue , if your seeing like 20% plus trims you either got petrol on your last fill with E85 tune or running wrong tune ie petrol tune on E85
also log AFR vs Commanded AFR and make sure that looks ok.
if that looks ok
I would modify the cranking IPW tables
Idle tables
Maf compensation after start
see wayno's posts here section on E85 cold start and Quiet start mods
http://www.ft86club.com/forums/showthread.php?t=94822