Serpentine belt squilling

I have a 99 Dodge dakota with a V-6. I just replaced the water pump and also the serpentine belt a couple Months ago. I replaced the belt tentioner a couple years ago. I have been having this issue for years, that every time I replace the belt it only lasts a few Months before it starts squilling loudly again. I spray lubricate on it to shut it up, but that only lasts a day.
Is there something else on the pulley drive line causing this? I was thinking the idler pulley maybe, but it spins smoothly as well as all the other pulleys. I've been putting dayco belts on it from Advanced Auto.