96 grand am Obd-2 codes

alright i went out and bought a code reader or whatever you may want to call it. i ran it on my 96 grand-am. There were only three codes that popped up when it ran. the first one was P0171-"system too lean. Bank 1"
P0113-"intake air temperature sensor 1 circuit high input" P0442 "Evaporative Emission System Leak Detected (small leak). I have searched a couple of sites on here and some post on this site about what these could mean they are pretty much self explanitory but my problem is each site and each post tells me different things that it could possibly be. i will say this..a while back when we changed my fuel filter we noticed there was a small leak in the gas line coming off the filter so we "rigged" up one with a piece of piping. So common sence tells me the "emission" leak could possibly be that. BUT woud this leak cause my car to not want to start then when it does it will start once then kill out then only crank over once then start making a grinding noise? and also when someone has it hooked up to jumpers it will keep cranking but as soon as you take it off the jumpers it will only crank the once like i said above. so any help with any of these things will be mightly helpful.