Guys, I need some help here. I have a 2004 Silverado, 2500HD 4wd. The knock sensors were bad so I replaced them. I got a new intake gasket when I put it back together and ever since I've been blowing these two codes. When I keep the engine under 2K RPMs it is fine, but under a load it loses power and starts to backfire. Fuel injector pressure is between 50-60. I'm at the end of my rope I've replaced the following: New intake gasket, new intake, MAP sensor, MAS airflow sensor. I can't figure out where the problem is. Also, another issue, may or may not be related, I'm having trouble at times with my brakes working...Any suggestions would sure be appreciated! Thanks in advance!