Narrowing down some LP issues.

[Miguello]

So anyone that has followed my dilemma with the sound on my LP, you know I am not really happy with how it sounds. Anyway, something clicked today, as I was plugging it in. When you plug it in, and the tip of the plug touches the outer part of the jack on the guitar, it makes a godawful squealing noise. I never really noticed before, because I tend to send the plug home pretty fast usually. It didn't seem out of the ordinary. But now I am noticing that if you touch it to the outer plug and leave it for a second or two, this ear splitting squeal emerges from the speaker. ALL of my other guitars, just does the normal semi loud buzz. I think I may be getting somewhere. Could this effect the sound of the pickups as well/ The three higher strings are painful to listen to, above the 8th or tenth fret. Not quite so bad on the neck pickup as the bridge, but yeah. The low strings have punch, but nowhere near the punch of my Green SG, or the new to me Dean ML. If you have a les Paul, and a $200 budget metal guitar sounds better, something is definitely wrong.

 

Could these two issues be related, and what should I look for?? Bad pot? Popped capacitors? crossed wires? The crossed wires seems a little doubtful, as I don't think anyones ever been into it but me, and all I did was look it over to make sure nothing was loose, etc.