about the loud clicking, now i can't be 100% sure about if it is exaclty the same problem i had. My car was making a loud clicking(more like loud knocking)around 3500-4000RPM, but i ignored because there was no CEL and the car was driving normally. instead of just replacing bad bearings i ended replacing the whole engine. if you just started hearing the noise get it looked at before you do more damage.
you can try the higher octane gas and it may be just the typical engine knock too.


95 SE MTX DH UIM, 65mm TB, SC CAI, Quaife, Centerforce, Fidanza, UR Pulley, F/R Strut Braces, Cross Drilled Rotors, S.S. Brake Hoses, 18" Enkei RS5, SVT Engine Mounts+Inserts, MSDS & y-pipe, Trubendz resonated exhaust & MagnaFlow cat