I'll give you a description of what happened. About a month ago my truck started shaking like crazy at about 45-55 mph (at about 1250 rpm). I fixed that by messing with my spark plug wires. My #3cylinder was missing fire. Soon after a got a used tip from a friend and welded it on in ag (I unhooked my battery but some kids hooked it back up while I was welding so they can listen to music. Not sure if that could cause anything but anythings possible). First my cat sounded like some material had shook loose and is rattling. Next, I cant get hardly get over 3k rpm, and anything between 2500 and 3k is a loss of power and speed. There is also a high-pitched whinning noise (that I can't pin point) thats really only noticable under 2k rpm. I also changed my u-joints about 2 weeks ago but didn't grease one of them because the fitting was wierd like a bowl or something but they came greased, just lightly.