Using more of your "go" pedal will help reduce carbon build up, the engine needs higher load and more than 3k rpms. Like every time you drive the car, go full throttle accelerating to highway speeds when merging. The more load and rpms that the engine sees, the less carbon build up. Shoot, if there is any way that the car could be detuned safely, I`d do that. Just so that I can go higher load acceleration without getting into as much trouble with the law. Granted I drive a GS300 that has the 2JZ in it, she purrs like a kitten and runs as smooth as silk. That engine regularly sees high load and high rpm situations, and granted is also port injected, however the Toyota motors are known for consuming more oil than the majority of other engines, nonetheless, the engine runs as smooth as silk with 165K miles on the clock and with seeing 20k miles (my ownership) of high load and high rpm driving, she runs better than when I bought her.
Often, with my co-workers, we get into conversations about how much horsepower is the perfect amount for the street and they always agree between themselves that 500 is the magic number while I always come in around the 300 mark. With 300hp on a reliable engine, the engine will be able to withstand being flogged all day long, thus increasing engine temps to the point where soft carbon deposits are being burned off. Burning off carbon deposits in a 500hp motor is much more difficult because the throttle input required to get engine temps to the point of soft carbon burning, result in very illegal speeds. Whereas in the 300hp motor, I can burn soft carbon all day long and get pulled over for doing 14mph over, instead of 34mph over in the 500hp motor.
Here in the states, our infrastructure just isn`t conducive to owning and driving German cars in the ways of which they were designed to be driven. The majority of german cars barely see 50% throttle application in day to day driving, when they were designed to see 50%+. Now, not all of the carbon build up problems are related to driving styles, BMW and other Germans have not been doing their best design work when it comes to building the engines. There is a lot of cost cutting by way of material use like plastics, for example using plastic parts on the hot side of engines instead of metal. At work, we recently had a customer who had been turning down the servicing of the EGR system on their F15 X5 35d and the EGR valve ended up getting clogged, over heating the EGR cooler, and together melting holes in the plastic intake. As their trade-in value was next to rock bottom, combined with the fact that no one wants a `14 X5 35d with 85K miles on the clock, the customer decided to bite the bullet and fix the X5. The bill was about $4k in parts and labor. Since the fix, the X5 has been in for other minor services and I have noticed that the owners have started to neglect keeping the exterior and interior in as good of condition as when I first saw it.
Long story short, give liberal amounts of acceleration up to posted limits, do plenty of walnut shell blastings, and take care of the car. And when going on short drives, like running errands, get the car up to temp and plan some extra time to do a few full throttle pulls onto your local highway or service roads