I'm totally laughing my a$$ off now. I searched for weeks about this problem when I was going through it, and couldn't find any relevant information. Now that it's fixed, I see there were a lot of others going through the same problem. I guess I just wasn't searching for the right keywords...
No offense to Gadget, but a lot of the stuff he was saying was just not making practical sense, and I would think that he (and others) would consider a $5.99 part over more extensive tuning and additional aftermarket parts - especially if this problem is somewhat commonplace.

But whatever. It's fixed, the truck is SUPER fast, and the world is a better place with my blood pressure back down to normal these days... <img src="/forums/images/graemlins/cheers.gif" alt="" />

Thanks for the support, guys. <img src="/forums/images/graemlins/patriot.gif" alt="" />