2004 yukon no power

[remy82]

hi
first off im new here but running out of options and i use forums for my atv and they help. i have a 2004 gmc yukon slt 5.3 with around 160,000 went to store the other day and was leaving i gassed on it hard and noticed that check engine light came on and was blinking so i took it to mechanic was reading p0300 code and running rich in bank one and bank two so..... had him to new plugs plug wires and replaced a couple of coil packs it ran worse so had another mechanic he told me maf sensor so replaced that truck runs much better but still at half throttle or full throttle i have no power and wont shift out so took it back and he told me that my icm was bad ignition control module and i didnt think my truck had one also did have b&g throttle cleaning done note also had a bad flood at work a few months back got lots of water and mud under hood it ran like crap for a few days then was fine..... i have mild things done cold air intake shorty headers a custom tune and straight dual pipes pls help i need it for work tuesday in new mexico sorry so long thanks

 

[austinfranze]

Have them check the fuel pressure. My tahoe runs fine, but has low power. They told me its the fuel pump. Mine has about 48 psi fuel pressure where it should be 55-63. Is it starting right up when you turn the key or does it take a little bit of turning over before it'll crank?

 

[remy82]

That's what i was thinking, but it cranks fine and idles fine. When i give half throttle or more check engine light starts blinking and i have no power. Several people have told me my cats or o2 sensors, the mechanic told me pcm. When i replaced the maf sensor it started running much better but still has the power issue. I'm completely stumped and have put over $800 into trying to figure this out.

 

[OHSIXX]

Sounds like a bad cat to me....I'd look for a new mechanic too.......

 

[remy82]

Yeah going to try that tomorrow when some shops open up thank you