Hello hope I am posting in the correct part, I have recently bought an l200 4life 2.5 with 119k on it. I have had it a couple month now and all has been going well but I got in it one morning and upon acceleration it started screeching but only Above 1800rpm. I thought belts to start with so tightened alternator belts, not sure on how to do fan belt but it seems fine and is pretty new since it was last changed. And timing belt has been changed recently too.If i come off the throttle the noise immediately stops but returns when I use throttle again. Any ideas?