sensor on top of intake manifold?

So i'm here asking what the sensor is on top of the intake manifold is and feeling like a complete noob. I honestly have no idea what it is. All I know is im replacing my exhaust mani and while I have the intake off im gonna take it to work and have it cleaned in the parts washer. so I take this sensor off and noticed its really gummed up and was wondering if I should replace it but have no idea what its called. I have a 99, and the sensor sits just in front of the TB. thanks in advance and for not picking on me too much

It's the MAT, air charge temperature sensor. The computer uses that and the MAP (pressure) sensor to determine the density of the air in the combustion chambers so that it can correctly size the injector pulse. It's a good idea to replace them every few years since they get coated with whatever crap ends up in the air intake (unfiltered air from vacuum leaks, blow-by from the valves, etc).

Good response Ehall, thank you

Thanks, i pulled it off and was like what the hell is this for? I was tired and covered in rust and PB blaster and just wanted to go to bed because i was up for over 24 hours. how much do they usual run?

I've checked on this one to... Dealer part, Special order (at least for my 91) . Will run you about $60. If i recall the dealer calls it IAT -Intake Air Temp sensor.

rockauto has them for $24 regular, $13 closeout