Best is to use teflon pipe thread tape, but use very little and only the upper threaded part of the nipple so none gets into the orifice.

In my 500k miles and three 89-92 245's I've never removed those brass nipples, just use the TB spray directly into the orifice and nipples, both directions, blow out with compressed air, do it twice.

Use a toothbrush on the TB throat around where the throttle plate contacts the TB where the two aforementiioned small orifices are. This area of the TB is the most important part to get squeaky clean. Prop open the throttle plate so you get into the corners. This effects idle control immensely!

Judging by the look of your TB, the crankcase breather has been busy, and I would look at the flame trap and all the hoses and nipples especialy the one from the top of the flame trap housing to the intke manifold. Those two small nipples I would take out and clean. You may find the hose and nipples completely clogged shut with a TB like yours.

While your at it, remove the IAC valve and clean it also. I use 50/50 mix of carb cleaner and WD-40 and a Q-Tip.

FYI the LH 3.1 throttle sensor doesn't need adjustment like the LH 2.X switch, but I leave it on when cleaning the TB, too.