2 new owners plus general fuel & PS talkies

[floatingkiwi]

Gidday all
Thought I'd finally say hello formally!! Firstly, my mother and I are both proud owners of 1992 Burgandy/Black with spoiler!
Mine is 85K KM and hers is about 150K km now.
I've been following the sites here for a few months now, and gleaning some marvellous pearls of wisdom too I must say.
However, I've got some issues I would like to get some more pearls on (PLEASE FEEL FREE TO MAKE ANY COMMENTS!!)

Fuel:
I've got some sort of foam/oiled air filter in mine that I can't make out the brand of. One would expect it to be better than the standard?? Brand new fuel filter. I am unfortunately also in the league of terrible fuel economy, even though I drive her fairly smooth. I was reading about the possiblity of O2 sensors and/or plugs, and am fairly technically competent (I should be, I'm an engineer) so I should be able to tackle these things myself. I also have a fair bit of the old black fluff in the tailpipe too, but not overly bad.
My mothers one can get about 30 MPG, the best I can do is about 18 (same gas 96/98). Hers also has a completely different power/torque response too. Very intriguing - lots of torque down low but starts to run out of steam at around 5000rpm and even starts vibrating/coughing like that suby flat four sound. MIne however, pulls like a proverbial from higher up, but just keeps on going!! I've had my cam timing checked - the cracked guards were worrying me a bit.
My gas tank is always overpressured - is this normal? When I take the cap off it always breathes all over me.

Secondly, Power steering:
I just had the powersteering pump replaced by a local garage, and hasn't been quite right since. The pump is very noisy (like a bearing whistle) and I get that slight surging/vibration through the wheel on cornering. Also my mother's car (at 150K) has a steering feel that is much firmer and more rigid than mine (mine feels like the preload is loose or something?) Could this be the famous o-ring (which was replaced at the time)? They stuffed up my steering boots too - they crushed them and now they pop around every corner!!

Factory CD player:
Skips nicely on almost every bump and when cornering. Anything can be done?

Tyres:
My mums car is chewing a small bevel on the inside of the front tyres which destroys them in short order. Alignment is good.

Alrighty then, I've taken up enough of your valuable time!
I'm in the central plateau region of NZ.

Hope your New year is a good one all.

Floating kiwi