if your coilpacks are shagged, they are shagged all the time on boost
ie they dont magically work between 4500rpm and 6000rpm and then misfire city
when coilpacks are shagged it will misfire its ass off from like 3000rpm to redline (any amount of decent boost)
given you mention the typical flat spot / cut range for R&R id say check the basics
given you said youve only just had the car
it could be
a) it started since the service / timing belt,
or b) its always been shagged
so check the basics, check it with a timing light at idle, check to make sure your base timing is correct
reset the stock ecu, perform a stock ecu diag if you can with consult to check for any dead sensors or unplugged sensors