Rough Hot Idle - 1992 2TZ-FE - The Saga of Njordi

Yay! Way to persevere. Let's hope this particular issue is fixed for good, eh?

Some related info on the unreliability of very old connectors, for other people who may read in the future...

When I bought my '93 it had an intermittent non-starting problem. About once every 10 starts. Turn the key and no turn the starter. Very annoying. Starter worked fine, so problem was in that low current circuit to the starter solenoid. Whenever it intermittently failed to turn over I'd hold the clutch pedal down with a stick, crawl underneath and jump the connections at the starter to get it running. Eventually I went through the methodical process of checking every junction in the solenoid circuit by unplugging the connectors in sequence and testing for voltage. I got to the point where the only remaining connection to test was the final frame ground. I wasn't sure where this ground point was so I never tested it, but I never had the problem again. I believe that unplugging and plugging back in one of the connectors cured a bad connection in there.

Ditto with the windshield washer fluid motor. Motor worked, column switch did not. Voltage getting to all connectors when disconnected and tested. Has worked fine ever since.

Let it sit for several days and see what the tailpipe smoke looks like.