Toyota Highlander year 2000 Someone ended up putting maybe 3 quarts to much oil. Instantly blowed smoke out the back. And i drove it about a mile because of power loss. The mechanic said it was ok to burn the extra oil. Stopped after that mile drain about 3 quarts out from nut. Now it hasn't been smoking a lot but, has strong odor, sputtering, and power is slow. It already had a misfire and now it's not good. I have drove on the highway about 55 miles. What to do now?
Try and pull the spark plugs. I'm suspecting that much oil burning cooked and covered the plugs and the combustion chambers in a huge amount of carbon. If the plugs are totally black and covered with deposits or even wet black, you may need to change them and try to clean the chambers out. I'm not sure where on the HL the PCV dumps back into the incoming stream, but it could also possibly affect the throttle valve.
You could try some of the additives that claim to clean combustion chambers, Seafoam comes to mind, but I don't know how much good that will do. Best of luck.