testy spedometer/odomemeter/fuel gauge

[shortstaque]

My 95 civic has 200,000 miles on it, give or take. I bought her at 91,000 miles and she had a broken gas gauge then, and still does. I have always used the trip set each time I get gas, so I know when to refuel. Last winter, maybe the winter before, I noticed that when the weather gets cold the spedometer gets cranky. The car accellerates normally but the spedometer will only read up to 20 miles an hour, or it might pulse from 20 to 40 miles per hour for the first 5 or 10 minutes of driving, after that it reads more accurately (I hope). More recently (in warm weather) I have noticed that the odometer reading and the trip gauge do not advance sometimes at the begining of a trip. I recently went on a road trip and refueled and drove at least 20 miles before the trip guage and the odometer began registering milage. Obviously this makes my practice of tanking up based on the trip milage a bit risky. Any ideas on why this is happening and how I might fix it myself would be appreciated. Also info on fixing the gas gauge issue would be great. Thanks