2007 2500 mega cab mpg drastic drop

[beawrestler]

hey everyone, i have 2007 ram 2500 megacab 5.7L. My MPG drastically fell. I was averaging 11-13 MPG without a trailer or plow. Now I am around 9.3 MPG without a trailer or plow. Truck is running pretty normal except seemed to lose some power pulling trailer up hill while empty. I just had manifolds done. I dont want to buy a tuner to get better fuel mileage. Where do I start

 

[CorDog009]

I’m wondering if the cats are getting clogged up.

 

[beawrestler]

Cats are clear its not throwing any codes at all

 

[RamminMopar]

Complete tune up maybe?

 

[MADDOG]

Start with spark. Remove and inspect the plugs. Insure the gap is correct. Inspect plugs for damage, oil, excessive deposits or evidence of a lean condition.

Change the fuel filter.

Look for vacuum leaks near the base of the intake manifold.

 

[Oliver Closehauf]

Just curios what you mean by 'had the manifolds done" .