94 del sol si check engine light need help

[94delsolsi]

ok i was driving home from the gas station i had just filled up and my friend was like i want to see 0 to 60 in this so i did it shortly after that my check engine light came on and the my car felt very slow. When i got back i opened the hood and heard a slight ticking noise and it was runing really low rpms it was at like 500 juming to 600 normaly its at like 800 and stays there. today i puled the cylnder head and every thing looks fine there is no metal in the oil and there is plenty of oil. i am thinking i may get the knock sensor coad when i check it i heard that could be cause by geting bad gas. i am going to try and check the check engine light by jumping the two prongs and see if the light flashes but i am not shoure if thats the right way to do it any help world be greatly appreciated its has the 1.6 d16z6 in it. thanks for reading and any help.