2003 Chevy Truck Poor Performance and fuel mileage

ROB HAUBOLD

MEMBER
2003 CHEVROLET TRUCK
V8
4WD
AUTOMATIC
73,000 MILES

My 2003 Chevy 1500HD has a 6.0L in it that feels like it's "pulling hard" all the time. At 60mph it may need to downshift just to climb a hill. Pulling my boat this all gets much worse. Fuel mileage is down, around 6mpg in town and 10mpg highway. Also with cold morning starts I will sometimes get multi-cylinder misfire codes. No body seems to have any idea why including the dealer. They did the recomended throttle body cleaning and sent me on my way. I would be greatful for any advice.

1 Reply

GFIMOTORCARS

MECHANIC
673 POSTS

I would definately recommend a tune up. With GM vehicles I have worked on with issues of poor performance and fuel mileage occur usually around 60k. If this is your case a couple hundred bucks in parts and a Saturday may get some much needed kick back in your truck. Start with a new fuel filter and a set of spark plugs and wires. Also get some fuel injector cleaner and send it through the tank. This is also a great time to check your belts and fluid levels. When you change the the plugs note any severe wear on the ends of the spark plug. Here are a few pics to help with spark plug diagnosis. Keep in mind abnormal spark plug wear can cause interesting issues with misfiring, even intermitent one's.