2012 Chevy Silverado 2500HD
110,000 miles
Lacks power and idles rough after you let it idle for awhile. Otherwise it seems to idle fine.
At first it had a code that said multiple misfires.
I decided to replace spark plugs and wires as it was time anyway. That code went away but still lacks power at times and idles rough sometimes especially if you let idle for a long time. I then replaced throttle position sensor and still have issues.

do I need to reprogram idle? I have a cheap code reader not one that tells me how to relearn.
Could I be looking at a fuel pump?

thoughts?

 

You could. Measure the fuel pressure and perform a leakdown test.