my engine loses 2-300 rpm when kicked in to passing gear. on 2003 Chevrolet Silverado 2500 HD

I have replaced the rubber fuel lines. the check engine light came on but went off before I could read the codes.

Codes are still there, unless you have removed the battery cables for some reason. Computer has a good memory!
Turbo working?
1 more answer
scan codes and post so we can adv