2003 dodge ram 4.7
what could be the reason the gas mileage has bottomed out.

 

What was it before?
What is it now?
How did you measure it?

 

you need to provide more information than that.

 

Did it just happen out of nowhere, or did you do something to the vehicle?

 

Small displacement 240hp V8 pulling around a 5000+lb truck with a crappy power robbing trans; why is my mileage sh!tty lol? Physics. Physics is why.

 

It was getting around 17 mpg on the hwy
Replaced the camshaft and crankshaft sensors and the throttle control sensor and lay time I checked for 6 gallons of gas I got saying 46 miles which equal it to about 8 miles a gallon.

 

What was the reasoning for replacing those parts?

 

It would crank but no start

 

Six gallons ain't enough to give you an accurate calculation. Heck, I burn six gallons sitting in traffic. LOL. Fill tank, zero odo, drive till light turns on, fill tank again and divide miles driven by gallons pumped.

 

You may need a new oxygen sensor or sensors. Is your engine oil level ok, and/or not due to be changed?

It could be a bad/older tank of gas. Did the service engine soon light come on? A dirty air filter and or throttle body does not help. Try running a tank full of gas with a can of Chemtool fuel injector cleaner or Marvel Mystery oil/alternative cleaner, that can help. The Ethanol in the fuel does no good for our mpg or the parts of the car. It makes the gas go stale after a few short months, retains moisture, gives worse mpg and It’s very corrosive unfortunately. Good luck!!