D15B2, IAT is on runner #2 and quite close to the head. When trying to remove the original IAT sensor, the plastic on it broke off and fell into the intake manifold. Would it be possible/safe to just remove the intake manifold from the head without taking all the stuff off the manifold, save the necessary coolant lines? I ask just your opinions/advice.

 

Yes, it’s possible.

Undo the fuel lines, the coolant lines, vacuum lines and anything in your way to access the bolts and nuts that hold the manifold on.

take it off, buy a gasket scraper and clean up the head and intake manifold flange, fix your IAT, and put it all back on. Easy peasy.