noticed the other day at above 3500rpm on wot the engine runs really rough, then hits limp mode, the eml didn't come on. once i got home i got the following codes 16684, 16688, 16686 which i understand to be a missfire on 2 and 4. i've driven it since but not gone passed 3k rpm and it drives fine and the codes haven't come back, I've not taken it passed this incase anything gets damaged. s3 with a 4yr old stage 1 map, coilpacks have been replaced since being mapped. what can I do to start eliminating this issue and what could be the potential cause for the missfire on both cylinders. cheers.