I'm changing the intake manifold gasket on a 1997 1500 extended cab with a Vortec 5.7ltr. While disconnecting...everything... I noticed a broken sensor. The sensor's location is drivers side, above the exhaust manifold, between the #1 & #3 spark plugs. It has a single purple wire that runs to a plug near the intake. It screws directly into the block. I'm guessing it is some sort of temperature sensor but can not find any info on it. Any ideas?