To anyone that has had this issue please help I own a 2004 silverado 1500 I have done the following full long tube headers, full exhaust, intake, and tune,..... Now just started last week it came up with a p0300 multiple misfire and It was a spark plug that was not screwed in all the way so I fixed that problem, but then it still had a p0171code which is running lean so I I put brand new all 4 02 sensors and no more codes, it ran good for 2 days good power then started running sluggish, and doesn't have any engine light.. When I disconnect battery for 30 min and reconnect it runs fine full power again for 3 to 4 miles then it starts with the running sluggish again los of power.... Now I'm thinking this can be the tune went bad. The truck idles fine, and no hesitation.

 

Problem solver bad knock sensor, I'm pretty sure they went bad from mixing avgas with premium fuel