i think my injectors are going bad or something. my truck gets around 9mpg around town and i got about 14-15 mpg driving from new jersey to kentucky (65-70) not towing. it usually has a little black puff on startup and then goes away. also i notice the throttle hangs sometimes when i romp it fast and the truck keeps going for a little while. i ran some powerservice threw the tanks and i made no difference. its auto with 4.11 gears. any way i can find out for sure without pulling the injectors?