Q: I changed all 6 spark plugs on a 06 avalon yesterday and when i got it all put back together the engine shakes and shuts off

Hello, thank you for writing in. A simple spark plug change can turn into a nightmare for anyone if they are not careful. What typically happens is that you screw in and tighten the spark plugs too hard. When this happens you close the gap on the plug, where the spark is created. This will cause the vehicle to misfire at that cylinder, and if enough spark plugs are effected, the vehicle can stall. You will want to start by removing the plugs again, rechecking the gap on them (with a special gaping tool that is very cheap), and then reinstalling them more carefully. If this does not solve the issue, you want to look further into the ignition system, check the wires for proper connection and routing, and seek professional help if needed.