Should I get my car checked out?

Hi, so I drive a 2005 Ford Focus with 49,000 miles on it. I have to leave it at home in September when I go to college but before that, in June, I need to get an inspection sticker so I can drive my car the summer. However, the check engine light has been on for 8 months, which means I can't pass. My car has also been making a rattling sound near the front tires (just got them replaced so its not the tires), and the acceleration has been pretty bad, especially on the highway. My dad says to just let the car get run to the ground so I don't have to spend money, but I think that the issue is just going to get worse, and I also need an inspection sticker (unless i just drive without one?). I'm guessing that the issue is a torque converter issue, oxygen sensor, or fuel injector pressure sensor issue. My dad says its just cuz its an old car, but I feel like the loud rattling sound and the terrible acceleration, and the check engine light indicate something is wrong? Is it worth getting looked at by a mechanic? I need the car for the summer, and after that I will need it just during school vacations and summer.

Your car will not pass inspection with a check engine light on. It could be something simple like a sensor. If it costs less then a tow bill, your dollars ahead. Most auto parts stores will pull the codes for free (Advance, AutoZone, etc.). If you don't fix it and it blows the motor, then you will have to buy another car. There are old cars with 400,000+ miles, that still run good. Old cars don't make noise, damaged cars do.

Fords rattle. They have since the Model T. But everything else should see your friendly mechanic.

Your dad's mechanical advice is not running on all cylinders, but don't trade him in just yet. In about seven years he will be a lot wiser, as Mark Twain observed.

I would

Get the trouble codes read. Likely a stuck EGR valve. The rattling could be detonation if so. It will eventually wreck the engine.

Your old man is a bozo. Why have you been driving for 8 months with the CEL lit? Any auto parts store reads OBD II codes for free! Go get the codes red and write the actual codes down… NOT hat the sales person thinks is wrong and then post the codes here for some help.
You automatically fail inspections if the CEL is lit.

If you need the car you should fix the car.

Simply have the codes read by your favorite local area mechanic have have it properly repaired.

Pull the trouble codes and have the issue resolved by a good mechanic. Anything loose can rattle. I wouldn't even try to guess from my chair. The problem isn't going to heal and the car will not respond to argument. Wrenches and skill are what's needed.