Had this same set of symptoms, in my case turned out to be a headgasket in danger of imminent failure. Unfortunately I didn't catch it, it overheated, cracked both heads, needed and engine swap.
Had this error for a good while. Head gasket blew a few miles from home, and was overheating before I noticed. Two cracked heads, I sourced a new(er) engine to fix the problem.
Deal with it properly before it gets worse. Replace that head gasket.
Hang glider rack
Hello, new user here. For those that don't know 3rd gen 4runners are a fixture in the hang gliding community, so even though it's been a few years here's ours with custom hang glider top rack, front support and the gliders on top:
