This is my first post here (although I've been stalking this forum for years to get advice) but I've finally come to a point where I need my own thread. I've got an 01 X, 2wd, 150k. Only modifications (performance wise) are a K&N intake and an intake manifold spacer. So I got into changing the valve cover gaskets (30-45min job, easy enough) but when I got everything back together and cranked it, 10 separate engine codes (had zero to start with). The main two were MAF sensor and Knock sensor related, so instinctively I just cleaned my MAF....to no avail. After dropping $150 on a new one I have a new lineup of codes. Knock sensor (x2), system too lean, some o2 codes and finally "random multiple misfire" (x3). The misfire is what I'm concerned about. Prior to the gasket change everything was in tip top shape with no CEL at all. As of October, the following have been replaced: plugs, plug wires, intake manifold spacer (with gaskets), TB gasket, MAF sensor (yesterday). Any suggestions would be great. I have a continuous CEL that flashes under even slightly above average acceleration and a SIGNIFICANT loss of power from idle to 3000rpms then it picks straight back up to normal.