[gsxrken]

Any time these cars don’t run right is a good time to verify your cold and warm fuel pressures. That said, I wouldn’t be surprised if your plugs are fouled with the way you use the car. The stock plugs run cold anyway and need a good Italian tuneup now and then, but 20 mile round trip trips will barely warm the car up. Your oil is probably a bit foamy too by not getting hot enough for long enough to burn off the condensation produced by all those short tips.

If you know your plugs are clean, and your timing advances properly (not stuck at one #), it’s worth checking your intercooler orange o-rings for boost leaks. It’s more common for these cars to run ok until 4k and then have issues at higher RPM levels, whereas you are saying the opposite. Perhaps you have a leak that affects lower RPM but is immaterial or less noticeable at full boost.

Be sure to come back and let us know what it eventually turns out to be… we’re all here to learn.