The gas mileage and power on my 2003 Toyota Avalon XLS has dropped. The auto mechanic suggested a fuel injector engine flush first and if the problem remains to replace the spark plugs. I paid $ 100 for the fuel injector cleaning and the gas mileage has improved somewhat but is still 20 % what it used to be. The mechanic wants $250 for the tuneup which seems excessive even for iridium spark plugs that cost ~ $ 7/ea. i would think that a number closer to $ 120-150 would be more reasonable. Mechanic rates are $ 65/hr. Am I missing something in my assessment or something else involved in the tuneup that wasn't the case 20 -25 years ago ( when i changed my own spark plugs).