1999 Pontiac Grand Prix Service Engine Soon light, error P1

My service engine soon light came on on my 1999 Pontiac Grand Prix, and I took it to Autozone and they came up with the code P1441. The probable causes for this error are listed as 1. Failed canister purge solenoid, and 2. Failed fuel tank pressure sensor. Sometimes when I start my car (and everytime I put gas in it), it will look like it is going to start, but then the RPM guage drops back to 0 and it shuts off. If I give it a little gas when the RPM guage rises, it stabilizes itself at around 700 rpm and runs fine. It never stalls out at lights or anything like that, just when I start it sometimes. I also went to Meineke and the technician there seemed pretty sure that it was just a bad gas cap. I have been driving with the car like this for almost a month with no problems other than the occasional trouble starting. Any help would be greatly appreciated.