Runs sluggish and stalls

[Blue01GTvert]

I have a 2001 Mustang GT, it started running a little sluggish and its stalls from time to time. Everything was fine until last week when I filled up at the gas station and went to start it. It wouldn't start and the theft light started flashing. I know that means there may be an issue with the PATS. I disarmed it according to the owners guide and the car started fine. But after that is when the sluggishness and stalling started.
My question is: Is there something that would cause both the PATS issue and the sluggishness? I'm in need of a tune-up, which I plan on getting ASAP, could that possibly be the problem? Or is it something more, like a bad alternator or something???

Sorry this is so long but I wanted to make sure I gave you as much info as possible. Thanks in advance for any and all help. :SNSign:

 

[COramprat]

A weak battery/alternator may cause some issues with the PATS and some sluggishness due to the injectors not cycling properly. Have themn checked to make sure they are not the culprit.

 

[Blue01GTvert]

A weak battery/alternator may cause some issues with the PATS and some sluggishness due to the injectors not cycling properly. Have themn checked to make sure they are not the culprit.

I was gonna get the battery and alternator checked but I figured I would take a look again first. It ended up just being the negitive battery connection, I replaced the battery terminal and now it seems fine. About to take it out for a spin to make sure. A problem I figured would cost me an arm and a leg may only cost a few dollars. Thanks