Civic LX 97 not-so-stellar-performance

Hi,

I got this Civic LX 97 a few weeks ago. I checked the engine
compression, it is OK, all cylinders 158-161psi.
I also have a 2001 Civic LX that my wife drives now. Both cars are
manual transmission.

Here is what I notices:

Acceleration: the 97 accelerates noticeably slower than the 01

Power/torque: When I climb a hill, I have to downshift 97 one more gear
compared to 01: let's say I use 3rd gear on 01, I have to use 2nd gear
on 97, to climb the same hill at the same speed.

Ping: I am not sure if that is a pinging sound or not, but I do hear a
different engine sound every once in a while when I drive the 97. I
could be wrong here though

Gas mileage: I get 27 mpg city compared to 30-32 on the 01.

So, what can I do? my next step would be to replace the sparkplugs, run
a fuel injector cleaner (Techron? I heard good things about this stuff)
and see what happens. Oh, I am also going to replace the air intake
filter.

Any other things to check?
Thanks