OK so here's my problem.... i have a 2003 MIM fender strat, and im getting a lot of squealing from my pickups. they aren't single coils i routed out for a Seymour jb humbucker and i have a dimarzio air norton s in the neck and the mid pup is completely disconected. so ive crossed off 60 cycle hum. but when i pull my hand off of the strings i get a extremely sharp squeel at high volume levels and theres an annoying humming coming from the guitar until i put my hand back on the bridge. anyone have any idea
Grounding problem.

Ground the bridge to the back of the pots, and check they're grounded to the jack.