I have a 1986, which should be almost the same, mechanically (4-AC
engine), and it has a timing belt.

The Toyota manual says that rough idle or stalling can be caused by
wrong idle speed, a clogged slow jet, wrong idle mixture, fuel cut
solenoid stuck closed, bad fast idle speed setting (only for cold
engines), choke valve open too much (cold engines), EBCV open, EBCV
hoses, or outer vent control valve opened.  The EBCV is a solenoid
operated air bleed for the carburetor and is a cylinder at the
passenger front side of the engine compartment.  It should be closed
when the engine is cold or idling.    The outer vent control valve is
located just above the charcoal canister at the driver rear side of
the engine compartment, and with mine the short L-shaped hose had
become soft and had split open.

I had a problem with bad idle, hot and cold, caused by a tiny piece of
rubber flaking off from inside the fuel hose between the filter and
carb and clogging the float valve.  It caused trouble only because I
had installed an aftermarket carb kit a few years earlier whose float
valve had no filter to keep out such debris.  Also I was told that the
o-rings from the solenoid fuel cut valves can tear during installation
and clog passages.  Those o-rings in the aftermarket kit were rock
hard and brittle.

The Mitchell manuals that some libraries carry (print, CD-ROM, or
online -- the print version is the best) give almost the same fuel/
emissions information as the Toyota factory manual for this car does.