Timing and Idle Q

The ECU has to relearn some stuff after changing it. Undo the negative battery cable for 30 minutes, then run it for 20 miles with the new timing, and see if it's better. If not, I'd back it back off.

and in general in my experience, the idle will get lower with more retardation and a little higher with advance.

make sure your balancer did not slip - that will skew your reference points.

good luck.

a stockish motor should pull 15-20" hg at idle. I could be wrong (I post a lot), but werent you trying to track down a vac leak quite some time ago?

also, though it does not sound like it is the case, if you set your base idle too high, the puter will fight it trying to get the idle back down to stock trim. this can cause surging.

Some of your symptoms could almost be thought of as a surging idle - Jrichker's sticky at the top of the page might have some info.

I will also add that some folks report a hunting idle after the KAM has been cleared (battery disconnected for any amount of time) - it takes a bit for the puter to relearn where it wants to be. EDIT: Ourobos already made that point. My bad.

good luck bud.