[Christ]

You could be vapor locking the injectors, which would cause a misfire. The fuel, generally, is already something like 90% atomized when it comes out of the injectors anyway, which is part of the reason fo a high-pressure fuel system. (Higher pressure atomizes the fuel better). The way to attempt what you want to do is actually to just heat the intake air, because as you're finding out, you can't vaporize the fuel completely unless you have injectors that can either handle vaporous fuel, or extreme pressures required to keep the fuel liquid at that temperature.

If you want to continue the experiment, try monitoring temps of the fuel and starting out at normal temp, then heating the fuel slowly until you start getting the misfire code again, then back off the heat a bit.