Toyota - 4Runner :: 1997 - Randomly Stalling At Stop Light

I have a 1997 Toyota 4Runner SR5, 6 cylinder with 188,000 miles. I love my car, it's treated me well over the years. About 2 months ago it started stalling at stop lights, etc. Basically, any time I came to a stop and it was idling while in gear. I start it right back up and when my foot's on the gas, it doesn't stall. After 10 times or so I learned that if I took it out of gear the RPMs went up a little and it didn't stall. About 2 weeks later the "check engine" like went on so I figured, now it's time to take it somewhere. So I took it to a mechanic that I've been to before and trusted (here in San Francisco) and he said, "oh.. it's probably just an idle adjustment" so I think, great, no big deal.

After a few days he said wasn't the idle and that after testing he found that all 6 cylinders were randomly misfiring. So he needed to change the spark plugs cause they were down to a bare nub. I figured, ok, it's about time anyway. He said it could also be the ignitor?, he didn't sound 100% positive, but told me there's probably something wrong with it since it's pretty old too and that's all he could think of. So he changed all 6 spark plugs and the ingintor and the engine light was still on. It was stalling less frequently, but still randomly stalling.

He then said he was going to have his Toyota specialist friend look at it. His friend couldn't figure out what was wrong either. Then he sent to to the Toyota dealer, they checked everything they could think of, but couldn't diagnose the real cause either. Apparently they even checked the "Dynamic Balancer"? I'm not even sure my car has one of those. They might as well have told me it needed a new agonculator (totally made up word) for all I knew. So they had my car for 3 weeks and finally I said, enough is enough, these guys can't figure it out. After 3 weeks of hearing how much money they spent on other people to figure out it, I finally said, let's stop the bleeding. The car still runs and doesn't stall that much. The last thing they tried was 2 series of a fuel injection flush (decarbonize)? So they did that with not a whole lot of improvement. They also managed to run all the gas out of my car and by the time I picked it up, the fuel light was on and I took it immediately to a gas station. No joke, they burned about 1/2 tank of gas and didn't refill it.

After 3 weeks and $1000, they come up with "we don't know what's wrong, but use Premium gas and it might fix itself". In the end they told me they were down to only one misfire, cylider #4. Also, the "check engine" light is still on. Since I've gotten it back it hasn't stalled, so there's an improvement. But I'm no closer to figuring out what's wrong that's keeping the check engine light on. Needless to say, I'm not taking it back to these guys.