I would encourage you to purchase new OE parts for the lines that run from the lift pump to the secondary filter and onto the IP. These lines come with the banjo attached and I'd not recommend you try to add your own hose to the existing fittings.

Additionally, I'd be curious as to whether the check valve in the IP might be causing you any issues. It's the bolt that's right at the outlet of the IP where the line returns to the secondary. If the spring is weak, it could be allowing the fuel pressure to drop during extended periods of shutdown.