+1 on starting with techtron before pulling injectors, Techron has kept mine clean over their 180k life.
Re the fire extinguisher comment, the Carrera fuel lines are rather notorious for cracking/dry rotting and then leaking onto the engine. If not already addressed, worth checking/replacing -- see, e.g.
https://rennlist.com/forums/911-forum/493731-diy-carrera-engine-fuel-line-replacement.html
The other Carrera-specific weak spot worth mentioning is the DME relay located under the driver's seat. It can fail/develop cold soldier joints that can manifest through no-start situations, etc. Worth searching the forum for DME relay and, to cut to the chase, pick up a name brand DME relay to carry around as a spare.
You should also check the date code on your tires -- if more than 6 years old, get a new set
Finally, to alert you to/help you with another common issue, check to make sure that your interior dome light turns on when the driver's door opens/turns off when closed. The switch that activates this light also disengages a relay that provides power to the power windows when the ignition key is turned off and is a relatively frequent failure point. When the switch fails, the relay puts a small load on the battery that will drain it after sitting for a week.