I have a 2001 GS430 with p0440, p0441, and p0446 codes, all relating to the evaporative emissions. My concern is if I have a leak or a solenoid stuck open, that would be a vacuum leak. How would plugging the evap line affect engine performance/MPG/anything else. I live in Florida and they don't do emissions checks so it's not really a concern for me.

 

Better exposure for this in the 2-GS section. Moving

 

EVAP is only an emissions concern unless the purge valve is stuck open and causing a lean running condition. But other than that, it doesn't effect run-ability. To delete the system, you just remove the vacuum line from the purge valve and cap it off at the intake. Then it cannot have an effect on the engine anymore. However you should consider if you are fine with contributing to pollution. If you don't care, fine, if so, get it fixed. Usually just start by checking your gas cap. Does it close tight? Is the seal still there? Not totally flat? Not cracked?