going up hill and i have the pedal at probably less than one third down and i hear this rapid clicking noise from the engine bay. it's sitting at about 2 and a half on the tach by the way. Does anybody know what this noise is?

98 ES3

I had a clicking noise coming from my engine too. I got it checked out and it turned out to be mis-adjusted valve. The Lexus dealer put in a new valve stimm so that the valve had the correct spacing. As car gets older, valve spacing needs to be adjusted, else you start hearing that valve clicking noise. If not remedied within a reasonable time, your valve heads get messed up and need to be re-ground, which can cost several thousands of dollars. So I'd suggest getting it looked at.