This is where I found I am able to to things the dealer can't/won't. I have a 2000 Sienna, started missing real bad. Well, the first thing is to replace the plugs, they are not so bad, the 3 in back require a bit of patience. The missing started again. I took it to the dealer. They didn't charge $400, they charged $200. They said I put the wrong plugs in. It started missing again. I brought it to another, they said I had a cracked plug, cost me $100. Started missing again. I bought a OBD tester for a hundred, found the code, #5 misfire, I replaced the wires. Why wasn't the hi tech shops able to find a shorted out plug wire? I agree, engine cool, remove the plastic cowling, put your plastic arms on.