p0441? changed gas cap, still comes on

after i took my car to autozone , they got the code p0441. they told me i need a new gas cap so they reset code i bought cap/ then not even 5 mins away it comes back on again. any feedback on things i should check would br great. oh and under the hood it has a loud "hissing" noise. which i noticed yesterday. and i been getting horrible mpg.

Hissing sound may be a vacuum leak could give you some ideas but you didn't say what year it is.

its a 2005 dodge neon sxt. thanks for any info on this.

I have heard of people having problems with the boot that goes between the intake and the throttle body. I personally saw one that the hose for the power brakes came off. I am just throwing that in, as for the p0441 code it is referring to the flow rate of the vacuum lines from the intake to the purge valve and the purge valve to the charcoal cannister. The incorrect flow rate can be caused by a leak or blockage in them. A leak in one of them would be a vacuum leak