I have a 2016 f150 xlt with 5.0, I get a flashing CEL when getting on the gas, sometimes it will stay on after a minute or so sometimes it goes off. No loss of power, occasionally will idle rough and a slight rooten egg smell when it happens, it will do it every time you get on the gas to merge onto the freeway or to pass. Took to dealership and they replaced coil and plug on cylinder 4, pick up truck from dealer and that same night engine light comes back on and went off a couple days later. Now couple months later same problem dropped it off to the dealer again 2 days later they call and tell me it's a bad alternator, the truck has 19k miles on it have never had a problem with my battery being dead or losing power to anything or dim lights ever. Is it possible for a bad alternator to cause the CEL to flash and stay on? I'm not looking for what's wrong with it that's there problem to figure it out, just trying to figure out if they are just giving me a line of bull to hide something more serious or what. It took them 2 days to find and fix the coil pack and plug last time, and it took them 2 days this time to tell me it's a bad alternator. In my research a flashing CEL usually means a misfire which is what the code was last time, I don't know what the code was this time they didn't tell me. Looking for some other opinions on what might be going on, or if my dealers service department isn't the brightest. 2 days to find a bad alternator and to fix it seems like quite a long time. Your opinions would be greatly appreciated as I am suppose to pick it from the dealer tomorrow if they get it fixed and would like to have some questions for them but im not a mechanic by any means and don't want to make a fool of myself, thanks