[CarPsyco84]

So is this a single cylinder misfire or the whole engine bogging down? Do you have a logger and or a Wideband? If its spark related it usually gets worse when its on boost, but it depends on how much boost and the fuel your running. Check your spark plug gap... should be like .028"-0.32" Or just get new ones if they are old. If you could figure out why your CEL is from that could be helpful.