I got my dad's 91 camry with 380,000 miles on it to pass by cleaning out the engine with seafoam. And on the next tank of gas I put in 93 octane gas instead of the usual 87. That might help, but I would definately put in the bottle of alcohol too, any octane boost should help the engine burn cleaner. My dads camry wasnt off as much as your 4runner but I thought it might help anyways.