My '99 with 150,000 miles is developing what I'm pretty sure is lifter noise. It is most obvious when at idle when warm, with the A/C on. When you do this, the thing literally sounds like a diesel, and I'm not exaggerating. Turn the A/C off, at it gets much more quiet, you can still hear a slight tick, but not nearly as bad. With the A/C on if you rev the engine up, it will also become less obvious.
Lately I've also noticed that at around 3700-4000 RPM, if I start accelerating in 3rd or 4th gear, there is a range in there where I'll hear it too, probably up around 4200. At this rev it sounds much different of course, but it still sounds like clatter.
Does this sound like something that 2Twisty's ATF flush might help?
Thanks,
-Tim