Im getting misfires on all cylinders. Using the snapon scanner i can see it at about 2000rpm. Doesn't happen at idle. I just recently changed the cap and rotor. The plugs and wires arn't new but not original, if the problem was there i don't think it would misfire all cylinders. A buddy at autozone let me swap out an ignition module and that didn't change anything. It doesn't throw any codes for misfires, but i always have a check engine light on for no cat. Also recently I had to do an intake gasket, valve cover gaskets, and a water pump, but i don't think its related to any of that because it ran fine for almost a month after i did those. What else to check?