1998 LSS hiss/shriek duing acceleration

Hey guys-

I'm sure this problem has been posted before, but I can't find it. My car has a whistle like sound as I accelerate during gears. I'm getting a new water pump and serpentine belt because they have to be replaced, but would they have anything to do with this? Also, I just noticed after filling up yesterday that my gas is going a lot faster than normal. I recently replaced the air filter, too. Any info would be greatly appreciated!

Thanks

Tough to tell from this desk, this could be the trans, bad alternator, idler/ tensioner pulleys, if performance is affected, a clogged cat. Someone familiar with this type of condition needs to check this for you on site.

maybe your a/c pump pulley bearings/clutch are going out...this also happened on my freinds corsica