My Car Is Driving VERY Erratically..please help?

Ok, so I got my Toyota Corolla, brand new, in February of 2010. There are now 22,452 miles on the car that I like to call my 'Piece of ****'...Anyway, ever since about 14000 miles, it's been driving really erratically, jolts ALL THE TIME...overheats, oil pressure light comes on...I just haven't brought it in to Toyota cause I haven't the time....my brother said it's cause I haven't gotten an oil change since I hit the 12,000 mile mark. I just don't have the time. I went at 3, 6, 9k miles for oil changes. Could that be it? Also sometimes, the engine makes a loud noise when I accelerate and I hear a metal scraping sound followed by a loud banging noise....I think the car is just utter $heet