where is the coolant temp sensor on my 1991 240sx se? I dont have an IAT and im looking for the coolant temp sensor.

Try looking immediately behind the power steering pump/pulley, just to the left of your rocker cover. There should be 2: one is for your gauge, the other is for the ECU. The gauge connection is a single blade connector that sits on the left (just to the right of the throttle body air hose), the IMPORTANT one is the multi-pin connector that stands straight up immediately to the right of the other. Sometimes these connections get corroded and that causes all kinds of problems. If you are running rich or have no power, this is something to check.