revs dropping low then bouncing back
 

1981 911SC. About 700 miles post- top end. Has been running well. Recently when coming to a stop and putting the car in nuetral or when shifting, the revs will quickly fall way down, and occassionally the alternator light will flicker, but car will not actually stall, and revs almost immediately bounce back to 950. It does it all the time, whether cold or warm. Car starts and idles perfectly. Any ideas?

It is most likely running a tad rich due to the hot weather. My '79 SC started doing the exact same thing when the weather got hot. I gave the mixture screw about 1/8 of a turn per others advice and the problem immediately went away!

That's counterclockwise as viewed from above to lean it.

Thanks! I'll give that a try.