I recently bought a Dodge 2500 with the 5.9 Magnum engine. It has around 220,000 miles on it, and the transmission was repaired about 10,000 miles ago.

While driving, I’ve noticed it feels sluggish—there's a slow response when I press the gas pedal, and it struggles a bit on flat roads and uphill. I’ve already done an oil and filter change, and I plan to replace the spark plugs later today.

I’m getting the truck ready to tow a car hauler up to 10,000 lbs from North Dakota to Missouri and back. What else should I check or replace to make sure it runs reliably and performs well during the trip?

 

Welcome to DF!

Pull the air filter housing, crack the throttle wide open, (engine NOT running.....) and take a look down in there. See oil pooling? Time to address the plenum issue.

 

There are a number of things to check with any new to you vehicle. All the fluids, brakes lights etc. Have a look at the brake line that runs between the frame and gas tank. They rust out and burst. If you are changing plugs get a cap and rotor and wires if you suspect they could be bad. And don't use overdrive when towing. If you don't have the external trans cooler it would be wise to get one. Transmissions don't like heat. If you don't know if the fuel pump was replaced add that to the list also.