Mirage 2001 Misfire

Mitsubishi Mirage 2001, 1.8L ES 4 Cylinder Mileage 11700.

I have the error code #300 first and made a tune up. After a couple of days, check engine lights up with error code #302. I changed spark plugs again. Misfire and check engine lights up again.

Vehicle vibrates especially when stopping at the stop sign or traffic when pressing break with transmission set to drive.

What can be the possible things?

Perhaps you could specify exactly what was in your tune up.

You also need to get the codes read again and find out if it is still P0302 or if it is another cylinder this time or perhaps back to random. You may find other codes as well. When you have that info, post back.

During Tune up,
Change spark plugs, air filter.

It’s still P0302, Cylinder #2 misfire.

You at least need to replace your spark plug wires also. If your car has a distributor, change out the cap and rotor as well. Sometimes carbon tracks form on the boots that go into the spark plug wells. Carbon tracks can form elsewhere as well, but this is a common place to find them, particularly on overhead cam engines.