I have been noticing my truck doing something strange over the past week or so. Truck in question is a 1985 Toyota Xtra Cab P/up, with just under 120,000 miles on it. Whenever I'm in 4th or 5th gear (don't seem to notice it in lower gears), and push the accelerator down past a certain point, it feels as if my truck has dropped into neutral. I can feel (and hear) the engine rev up, but the vehicle maintains the current speed. Spoke with a couple of my coworkers, who can't figure out why it does that. One of my coworkers thinks possibly a stuck e-brake would do this, but I can't see that being the problem, as the vehicle is perfect aside from this one problem. Anybody have any idea what's going on?