if this helps anyone, i have a 2000 toyota 4runner with 380k miles. i was experiencing a hard knock and shake at idle also while driving around 1700 rpms / 50/60 mph. i changed plugs coils and wires. problem was still there. checked timing belt, belt was good. checked for any vacuum leaks. all was good. ended up being number 2 cylinder was misfiring. i ended up changing all 6 injectors and now the truck runs like new. THESE TRUCKS ARE BEAST!!!!