'01 Impala, what would you do?

Okay, I bought my 3.4L '01 white chevy impala a few months ago for 1,800(off the street). I knew there were problems, but I couldn't beat that price. So basically I'm going to list all of the issues. Most of the problems I have a good idea of what they are, I just want to know what you suggest I do, or where to go to get it fixed.

Many of these problems are connected.

-Check Engine light is on
-Thermostat doesn't work (coolant level sensor?)
-Heat only works on level 5 (blower motor resistor?)
-A/C doesn't work (I live in NY, so not a big deal right now)
-engine fan turns after after I turn the car off
-fuel gauge off (not a big deal, not for the price to fix)
-Car gives off a bad, gas burning kind of smell when it turns on...?
-MPG has decreased gradually pretty much since i bought it. A lot of it i'm sure has to do with the cold weather, but seems like too much of a decrease.

-The engine makes a VERY bad noise when I turn it on in cold temperatures. Only lasts about 10 seconds. Kind of a loud squeeling noise, but I'm bad at describing things.

So what should I try and fix first? Or where I should go to get it repaired? Any ideas on the engine noise, or anything else? I'm 19, this is my first car, and I know very little about cars. Any help is appreciated. I'll answer any additional questions if I can. Thanks for any help!

Most of these problems are not too complex and are typical of a car which has been neglected by the previous owner. Cheap used cars typically need repair work like this.

My suggestions in the order you have posted.

1. Scan for codes stored on the ECM. There are websites that can tell you what the codes mean, but sometimes these explanations need interpretation to come up with a remedy.

2. Why do you think the thermostat does not work? Usually if they are defective, the engine never fully warms up; the heater does not push out much warm air and the temperature gause does not move much.
Thermostats are easily replaced and are pretty cheap.

If you change one, consider draining out the old coolant, flushing the cooling system and refilling with new, properly mixed coolant at the same time. Coolant does not last forever, if the cooling system has been neglected, its time for a change.

BTW the thermostat has nothing to do with a coolant level sensor.

3. You are correct, that sounds like a blower motor resistor. Usually the resistor pack is still good, but the thermal fuse has blown. If you are handy, you can find the thermal fuse on the resistor pack, and solder in up another one sourced from Radio Shack. However, most mechanics do not bother to do this, they just replace the entire resistor pack.

4. AC systems are best checked out by a qualified mechanic when the weather warms up

5. You mean the radiator fan? If the thermostat is stuck open the fan probably does not need to come on at all and it never comes on unless the ignition is on. The fan relay may be defective or shorted out.

6. In what way is the fuel gauge off? If it reads a higher or lower fuel level than is actually there, the sender unit in the tank may be bad. If the gauge is pinned all the way to E or F, and reads nothing in between there is probably a wiring problem.

7 and 8. The poor mileage and bad smell may be related. If the oxygen sensors are bad, or there is an ignition problem, the fuel mixture may be too rich and/or unburned fuel is going into the exhaust system. Both issues will cause poor gas mileage and will overheat the catalytic converter, creating a bad smell.
Note this condition may damage a converter so much it needs replacement. It also might be a fire hazard.

Also, this issue may be related to #1, shown above.

9. the bad noise sounds like bad bearings in one of the accessory devices, like the alternator, AC compressor, power steering pump or water pump. Sometimes you need to have someone start the car while you listen to the engine carefully under the hood to pinpoint the item which is bad.

#1,2,7,8,9 should be fixed first.

Wow, thanks. Much more helpful than I was expecting.

For the thermostat, I mean the thermostat gauge doesn't work. the needle stays to the left the entire time.

When I bought the car, I did a scan and it said something about the coolant/thermostat. I replaced the coolant temperature sensor due to advice from a friend, then reset the diagnostics or whatever, causing the check engine light to turn off, and also the engine fan (not sure what to call it, maybe the radiator fan) to not turn on after the car is shut off. Also, this caused the thermostat gauge to begin working again.

After about a week, maybe two, the light came back on, thermostat gauge ceased working, and engine fan turned on again. So, I'm not sure if a replaced thermostat would fix this or not?

And about the fuel gauge, it's..well, wacky. Seems to work when I fill up the tank. Once I get to about 3/4 full it stops working, slowly moves to F when I'm driving. The more I drive, the less predictable the needle gets, moving all around. I'm assuming it's the fuel gauge sending unit, and I'm not really worried about fixing it.

So as far as the bad noise, mpg, and smell, you think I should just bring it to a mechanic to get checked out? Any suggestion of where?

7 and 8 could also be a bad or leaking fuel pressure regulator. It is fairly cheap and easy to change yourself. GM made a bunch of bad ones, they were recalled a couple years ago. I think the 01 Impala was included in the recall. Seach the NTSB website for recalls on your car, if it is subject to recall, the dealer will fix it free.
9 could also be a worn our serpentine belt slipping when you start the car. Again, an under $50 do-it-yourself repair.

When the coolant temp sensor goes bad, the engine control computer (PCM) cannot tell if the engine is overheating or not. To be safe, it turns the fans on.
Bad oxygen sensors will usually cause the check engine light to come on, but not always. They cost about $80, and there are two of them. A scan tool will be able to tell you which (if any) of them need changed. You can change them yourself in about 15 minutes.

I will buy the car off of u