I have two rubber lines running down from the engine compartment on the drivers side of my astro that connect to two metal (approx 1/4" dia) lines that run parallel with each other towards the rear of the vehicle. There is a metal (possibly aluminum) pressure connector where the rubber and metal lines connect that is leaking. It seems to me that it only leaks when I first start the van after it has been out in the cold - it didn't occur all summer.

Can anyone tell me what these lines are for? Would it be possible that when this connection is not tight (i.e during cold weather) you would lose pressure and cause the vehicle to sputter and lose power when taking off?

What's it leaking?
Just a guess, but I'd think gas line
'96 and newer are about 60 psi, be careful

I second the fuel line thought.