He can probably see it dumping fuel when looking into the throats...........

Anyway,

I don't not-never-know chit about Toyota carbs, so please correct me if I am wrong....But I'm thinking one barrel is primary and the other is secondary. One runs all the time and the other kicks in under load.....If so, it is a vac secondary 2 bbl, right?

If that is the case, then your secondary bbl is getting the signal to flow fuel when it shouldn't....and that is what you are seeing in that one bbl that is dumping raw fuel at idle. And that is what is causing all your problems.

If all the above is true, then the problem is most likely related to incorrect vac hose connections. 80's carbed California stuff is a snake's nest of hoses. You can bet one or more is connected wrong.

good luck....and please tell us what you discover.