Well I'm used to diesel engines (my main ride ride is a 1983 Mercedes turbodiesel).. so I never quite heard of a throttle body..

To adjust the idle speed I just adjust the mechanical linkage.
I'll find it and see if I can adjust it up a little.
The reason why I want to do that is because the engine vibrates so much at idle in gear and the engine rotates a little (about its crankshaft as the axis of rotation) when it's put in gear. I'm guessing that maybe the rubber engine mounts are bad after all these years?
Funny thing is with the A/C on the vibration is lessened.
The problem is that when I stop at a traffic light (it vibrates) and I give it a moderate amount of throttle input the engine would act as if it was going to stall but it doesn't...
However, with the A/C on (increased idle speed) the engine idles perfectly and moves off perfectly. This is what led me to try increasing the idle just by a bit.
I've replaced the fuel filter, all four glow plugs (WTH?!@# Spark Plugs I mean) with Bosch Supers correctly gap'd, and ran two bottles of Techron Concentrate... none really helped.
When the engine is cold the vibration is worse and it would stall when I let moderate amount of air in suddenly from idle.
*Edited.. sorry.. been with diesels for too long*