Fuel Leak

I have a 1996 Voyager four cyl. It's been running rough lately i.e. hesitates during acceleration, misses any time throttle is applied (from dead stop or when on hiway). When I start it in the morning or after it's been sitting for awhile, I get a strong gas odour. Today I noticed gas leaking from the gas tank (drivers side). It looks as though it's leaking from a valve with fuel lines attached to it near the tank because the tank and valve are both wet. What valve is this and would this give me the problems I mentioned above if it is faulty?

Any ideas would be appreciated