[stownsen914]

The gas cap test is a sign. If you haven't already, check to see if any of the vent lines are actually plugged. If the tank doesn't have at least one clear vent to atmosphere, it will run poorly once the fuel pump starts working against a vacuum. Sort out where the hoses need to connect later - I think that will be secondary to poor running condition.

The things you plan to do all sound like good ideas. Personally I'd want to find the smoking gun before throwing replacement parts at it.

You may also have a fuel pressure issue (multiple possible sources), which might be the next thing to look into once you get your vents sorted.