Thank you for all who gave advise on this. The car had sluggish acceleration and rough idle, and it would come and go. So spark plugs, wires, fuel filter and fuel pump was changed (I thought fuel wasn’t reaching the engine) and problem came back again. Then I took out the spark plugs and compared them, #3 cylinder plug was darker than others so I guessed fuel injector isn’t working. Finally changed #3 cylinder fuel injector and that cured the problem. The injector was faulty and sometimes was working and sometimes not. Again, thank you! You guys are great!