[west_side_supra]

exhaust smell is from running rich. as for it starting fine when cold but dieing when warm makes me wonder if your injectors are messing up. the IAT "intake air temp sensor" is exactly what it says, it reads air temp to adjust the amount of fuel, the 02 sensor usally doesnt do anything, at least it never did for me. the nuteral switch is just for your clutch pedal, its a little switch that when the pedal is fully depressed that it hits the button so power can continue through the system to allow you to start it. i recommend testing your IAT first, because i have seen many cars run very like crap with this part messed up or missing. as for the location of the IAT i have no clue, thats something someone else could help you out with or look in the TSRM for all the information