2000 Jetta GLS 5-speed stalls at stop sings and in turns?

i just bought a 2000 Jetta GLS with 99K miles, when i start the car it has a low idle at first, like its about to die, then settles at 900rpm, then i give it gas and it is shuttery like its gonna die, and when im stopped at a stop sign or making a turn it will die, and the battery light comes on. I checked the battery and alternator there both good, i cleaned the MAF sensor, and unplugged it and the motor runs the same, so i dont think thats it. Also i have a code of p1580, im not sure if this has to do with the motor running like it is. Another thing is when im driving and i am accelerating and abruptly let off the gas it jerks, not side to side but like fwd, im very frusterated and would appreciate any help.