Honda Civic 2000, 109k miles. check engine light on, shakes, runs rough, loudly when i accelerate
 

My Honda Civic year 2000 is behaving very strangely. Yesterday i bought full
tank of gas and I parked it. I drove it like 3hrs later and it started run
rough and lose acceleration, shakes when i accelerate and then the "check
engine light" then came on. I took it back home and left it till today, and
then I started it and drive for about 20 miles and it still doing the same
thing. what should I do.