Hello,I have a 06 mega cab w/120,000 mi.on it I bought it with 80,000.it has always gotten poor mileage 14mpg to 16mpg I do alot of highway driving 50mi each way to work set cruise at 65 and go,never better than 16(this all hand calculated)ive changed all fluids to synthetic-motor oil,trans,diff front and back etc.tire pressure up 65-70psi,home depot mod on air box,smarty jr set on mileage settings, airdog150,no gauges.could I have bad injectors?Any suggestions on things that I can check?I don't have any faith in local dodge dealer.Any help or suggestions would be appreciated.Thank you Cliff