My 90 riv doesent start when it is below 20 degrees. I have purchased an intake air temperature sensor, does anyone know where it is located on the car. It is the same size and shape as the water temperature sensor and I can find that.

No diagnostics done here? The car should be scanned to check the readings on both the iat and the coolant temp sensor, when dead cold, to confirm the accuracy of the inputs to the pcm.