Hey, I've had the same problem in the past and it came back and I fixed it again. For me it was the IAC. The truck would rev up when the clutch was pressed in. It would happen a few times in a row then be ok and eventually do it again during a drive. About a year after I originally replaced it the issue came back, much to my dismay, and I have gone the past 2 or 3 months without replacing it. I just learned to deal with it by down shifting (or upshifting as the case may be) but it burns the hell out of a clutch and wastes gas. So I finally replaced the IAC yesterday and everything is cool again. I am keeping the old one and cleaning it (there's threads on how to do that somewhere) so that if/when the new one starts acting up I can just swap them out, clean the dirty one, and repeat. If this didn't fix it I would have moved next to the MAF. I got the IAC for $40 at autozone.
Another thing you may notice is that you get no compression braking from your engine, like if your going downhill it will cause you to accelerate at a quicker pace than normal without using the accelerator.
Hope that helps.