lets warm air in when it reaches a certain temperature.
under your air filter
The intake air temperature sensor is built into the MAF sensor on a 1991 Nissan pickup. It is between the air box and the throttle body.
yes
no
no
no
temperature sensor.
It seems that your thermostat is not opening.
in the gas tank, it is part of the fuel level sensor
sounds like a temperature sensor problem
below the raditor hose that's connected to the thermostat.
no 84 and 85 swap out.