Also- hood vents should not cause issues. I have a Boss 302S grille which just has netted holes/openings where the GT fogs used to sit (which allows more air into radiator and engine bar) and everything is fine. I have the Boss 302 fascia, so my fog harnesses now run down to smaller fog lamps at the bottom of the car (like a Boss). With this grille, though, the car runs cooler and during the winter, the ECU likes to throw a code if you get a good gust of cold air into the engine bay stating that the thermostat is not opening correctly.
This is correct, but it is also incorrect. Yes- the thermostat is not opening in the normal amount of time. But it is not due to a malfunction with the thermostat- it is due to the fact that the car runs cooler and takes longer to reach that temperature of which the thermostat opens. If you have a tuner like I do, it's not a big deal. You just clear the code and go on with your day. Just more food for thought. EFI has a lot of funny stuff that carb'd motors didn't have to deal with, so it takes some experimenting and sharing of information to know what each change will do.