Is there anything I can do to fix my car myself?

What year, make, model? What’s normal mileage you’ve seen? What’re you seeing now? How many miles are on the odometer? When’s the last time you had some kind of scheduled maintenance done?

Has the “check engine” light come on? You could be in a “limp home” state which would decrease your mileage. Are the plugs over 50,000 miles old? Fuel injectors need cleaning? Carburetor (remember those?) need adjustment?

What the hell is a ‘limp home’ state?

Try google.

@asmonet What my car is normally.

Without specifics on the age/model/condition of the car, we’re only guessing.
If you do take your car to a mechanic, take it to several mechanics and get several estimates.
There are mechanics who will try to take advantage of their customers.

It’s a 2000 Toyota Camry with about 120K miles on it. It hasn’t been serviced in a while, but it hasn’t been too terribly long… I haven’t been actually tracking the miles prior to the problems, but it’s only getting 30 miles to the gallon and I’m definitely filling it up more.

Mileage will decrease over time, but it sounds like time for a service call.
Seemingly little things like alignment can significantly affect your mileage.
On higher mileage vehicles, continuing to perform routine maintenance like changing the oil, changing air filters, oil filters, etc. is more important than ever. Most of these things car owners can do fairly easily.
Good luck with your car.

A subtle and potentially complicated problem such as reduced fuel economy isn’t really a good issue for a beginning DIY mechanic. There’s just too many possible factors.

I’d reccomend turning the troubleshooting over to a professional. Have them fix it, or if the reccomended repair seems simple enough attempt it yourself.

There’s something calming and satifying about performing your own car repairs, I just woudln’t suggest starting with diagnosing this particular problem.

Try spraying out the carberater with spray cleaner while the car is running it will blow smoke out the exhaust and act like it is going to die but keep on the gas and keep spraying, then depending on what kind of motor it is either put fuel injection cleaner in your gas tank after filling it or change out the jets in the carb or slow down the fuel mixture in the carb with I believe it is a 9/16 wrench. You could also change your plugs, plug wires, radiator cap, points, and fuel filter this would be a fool tune up and it should run like a champ.

I would DEFINATELY replace the fuel pump, seeing as a 2000 camry with 120,000+ miles on it needs a new one sooner or later. While you are at it, you will have to have the gas tank dropped down, so you should DEFINATELY not pass up the chance to replace Fuel Filter either. This should definately increase fuel mileage. Also, keep in mind it could be just leaking. If you really want to do the work yourself, just take the hoses that lead away from the tank, clean them off, cover both ends of them with tape of something similar so that no water can pass through the ends, and hold them underwater in a tank or sink. If there are no bubbles, you can most likely infer that there are no leaks. WARNING: Be EXTREMELY careful, and keep in mind that the car is 12 years old, not new, and has a lot of wear on it. Don’t be rough on anything.