i got a 90 f150 302 5spd 2wd sometimes only sometimes when its hot i get a squeaking, squealing noise come from the exhaust around the cat its pritty loud i can hear it from in the truck with windows up. nothing is loose its all about 2 years old the exhaust is . the noise will be there for a second then gone then back and gone i duno what it is no clue i work at a ford dealership im an apprentice in my first year been there a yar andf a half iv asked and none of the guys there know either. also sometimes when i shut my truck off when hot i can hear a squeeling noise much like the one i get from the exhaust but not as loude could it be the air enering the cat from the air pump? other then that i have no clue hopefully someone has a idea. tnks