Guys, I just took it to the Acura Dealership here in San Diego and it _was_ the valve clearance as I suspected. I had them also check the timing (which was fine) and replace the plugs. It pulls like it's old self (the bench mark its always stuck to was 4050RPM = 130 km/h almost exactly in 5th gear on level ground). After the trip it took about 4300RPM to do 130 clicks, but after the valve clearance was ajusted, the sound is back to normal and so is the power and feel. Apparently, it was producing less power at the same RPM - which was my hunch.

There was no chance in hell that my clutch would die after just 5 years - if your clutch dies before 8-10 years you shouldn't be driving stick