Recently my car was lossing power and having a rough idle...

So i replaced the cat, and the fuel filter...

And Everything was fine.....

I even took a trip to San Bernardino recently for the Inland Invasion Tour

Well this morning, I tried to start the car and it died. I told myself its because its cold out.Well i tried again....died again....tried again and gave some gas. The car moved but felt like it was being chocked. It intermitedly gave power and went away...

I havint had a CEL or any othermajor issues. The car has been smoking black for a while now...figured its just cuz its 16 years old....

Yesterday though....the cars idle was slightly rougher then normal, but i thought it was because the car was cold. And the car has been idling around 1k since i readjusted the idle control switch...

Just hit the 126k mile mark....

I havint changed the oil for a while....about 10k miles.....but i put slick 50 engine protector and whatnot and that high mileage oil last time i changed it....

WHAT COULD IT BE......PLEASE TELL ME ITS SOMETHING EASY.....i have a huge evolutionary biology midterm thurday and i need a damn car.