2006 2500HD 6.0 has poor acceleration, reduced fuel economy, and rough start-up.

What is your question?

At initial start-up my engine runs rough and sputters for just a min or so. Around town it operates fairly normal, but when trying to accelerate quickly there’s a major loss of power. It acts like it’s not getting enough fuel. My fuel economy has dropped down to 7-8 miles a gallon. Initially I had a code of P0446 and I replaced my Evap Canister, Vent Solenoid, MAP Sensor, and Purge Valve. I cleared the code, but was having the same issues. A few days later the Check Engine light came back on with code P0174 and P0171. I’ve listened closely and I can’t hear any air leaks. I don’t want to keep chasing parts if someone else has had a similar issue with better results. Thank you!

What makes this problem better or worse?

Heavy acceleration and the initial start up.

How long has your 2006 Chevrolet Silverado 2500 HD had this problem?

Several months.