ok on the first one it could be a multitude of things.  there are no tsb's on that problem.  I think that it might be something with the clutch being that u say it goes away when you are heavier on the gas.  could be that the clutch is not disengaging all the way when the system is getting hot.  this happend in my xj. I guess a way you might be able to test this would be does it go away when you press in the clutch?  the second question ummmmmm got me