OK, I have an Ibanez RG with an Edge III trem. I can dive with no problem it comes back perfectly in tune every time, but if i pull up even the slightest bit...even if my palm mute is a little too heavy..it returns sharp.
Hate to say it but your trem sucks, might be just a crap trem, i have a cheap ianez trem and i cant even touch it, it just stays there, no whammy or anything lol
^That's the only thing I can think of, I've tweaked everything and it's still the same. I was thinking of buying a replacement anyway, maybe an ESP with a real FR
if you like to wammy (like i do) then either get a diff guitar or possibly replace existing trem first. if you do the latter, it may actually increase the value if you are selling to someone who has already been thru what you have. If you sell it to someone who doesn't know about these trems then....