Couple Questions about my '91

Howdy dowdy, I honestly don't know much about cars.. I know how to check my oil/transmission/etc. and do all that fun stuff but I'd love to get to know my car better.

I have a 1991 Subaru Legacy (automatic) about 175,000km on it, I know when we got it, it had a brand new tranny 160,000k... and every person I've gotten to check under the hood, people at jiffylube, everyone has said that 'whoever owned this car before you has taken damn good care of it,' 'you've been taking care of her well' etc.

But I have a couple questions.

1) when the temperature outside is too hot or too cold, the CHECK ENGINE light comes on and my car rattles like it's about to fall apart into a thousand pieces like cars do on tv. what's up with that?

of course the idea of 'too hot' or 'too cold' is ambiguous... simply when the temperatures outside are either to the point where if you sat inside of the car, you would start sweating profusely if the windows weren't down, or when you almost lose your hands scraping down the windshield because it's so damn cold. sometimes it randomly does this as well. all the same things from 3) happen, except when I'm driving, it doesn't shake as hard as it does in 3). Also, if I accelerate to say, 50km/h, and let go of the gas, it stays at 50km/h. Doesn't change. Like it's on cruise control.

2) if we are saying the middle of the steering wheel is 12 o'clock, whenever i go past 6pm/am turning, it makes a clickclickclickclickclick sound. What does this mean?

3) I went through a very bumpy road (lots of rocks and stuff on the road for some reason — that road wasn't usually like that.) and after that, my entire car started shaking (similar to CHECK ENGINE light scenario - except no check engine.) My steering wheel was shaking back and forth vigorously as well, once again emulating the idea of my car falling into a thousand pieces. My girlfriend said I might need to get my tires balanced.

Please help this rookie — I just want to get to know my car a lot better than I do.

EDIT: it seems that there is a technical forum, I'll post this thread there because these may be more general issues than just the year of my car lol

I would start by cleaning your Mass Air Flow sensor with MAF cleaner. How is the water temp sensor? It sounds like your ecu is not reading the ambient air temps correctly. I believe that is a function of the MAF unless there is an IAT inlet air temp sensor also. Either way, it's a good start.

Your clicking sounds like a CV axle, check the axle boots for tears, a sure sign of bad axle.