Here is where the confusion happens. You cannot run a San Andreas ISO on a PSP,
Keep in mind that playing GTA: San Andreas on the PSP may require some technical expertise and patience. If you're not comfortable with custom firmware or potential performance issues, you might consider exploring other gaming options. how to play gta san andreas on psp link
Full PC version with good graphics. Cons: Lag, low resolution (480×272), PSP controls can’t map all PC keys easily. Requires the PC to stay on. Here is where the confusion happens