Hey this is my first post to the forum to I hope i am in the right place. I have a 2008 mustang GT 4.6 with only intake and exhaust mods that occasionally the CEL flashes for up to 5-20 seconds of which during that time I experience severe power loss. Once the light goes off the car runs fine. I did some research and found that a flashing CEL means the mustang's computer has detected at least one or more misfires on the cylinders. I just took it to the dealer today because they told me this was a problem that needed to be solved ASAP because it could cause serious engine problems. However, after spending almost $100 running my ford dealerships retarded diagnostics (because i thought warranty would be covering this malfunction) they told me they couldn't find any problems with my car at all and that its in great running condition. So, here's my main question if there is anyone out there who can help. Since I can't produce my car experiencing the problems to the dealership when it is actually screwing up, how do I figure out what's going on with my car since this is still an occasional problem? My fear is I am going to screw up a lot more parts continuing to run my car in the condition it is in but I don't even know where to start when so many things can cause an engine to misfire. The only things I could think of is the fact I am 4,000 miles overdue for a fuel filter change which will be taken care of soon. Has anyone experienced this problem before and if so were you able to find a resolution? I am open to any and all suggestions all help is greatly appreciated. Thank you.