Actually, both GE and GTE have "idle screws" they're NOT considered a serviceable item at all. There's a reason they're not even covered in the TSRM.
As a side note, I've seen people adjust the WAY wrong things before when trying to adjust the idle... and effectively doing so but at the risk of causing damage: dash pots, air regulation screws and my favorite..... over tightening the throttle linkages so the throttle plate is always partly open and the IDL switch is never closed.
