I will correct the vent issue by running a separate vent thru hull as opposed to having in the fill cap....
This is confusing. Let allow me to explain > in all the above posts there was an initial thought that the venting of the tank was the issue. However, there is no conclusion to that effect. Yet your post suggests that that is an issue.
Is it? Have you validated that after the engine dies that unscrewing the gas cap
did not solve the problem?
While I am being blunt it is not intended to infuriate you. The key to solving issues to thru a process of elimination. A perfect example of this are posts 21 thru 23. This process outlined by AllDodge provides either this or that based on the testing.
More: a simple fix to a combo fill / vent issue if it exists (i.e., not venting) is simply to replace the cap. They are cheap and I recommend carrying a spare > when that little ball-chain breaks during a fueling and the cap is now 10 feet underwater you will be glad to have that spare.
More More: installing a “new” tank vent is not something to be taken lightly. See this
link for the requirements (paragraph 4.13).
In conclusion: I strongly urge you to NOT add in a separate / new tank vent. Change your cap if needed. And to also follow the great advice you are getting, step by step.