2009 GMC Sierra 1500 5.3L Flex Fuel Low Power and Missing when driving uphill.

[jridenour201]

I have a 2009 GMC Sierra 1500 with the 5.3L V-8. Here lately I have noticed it is starting to loose power, and when in overdrive and you hit a hill you can feel it start to run rough and miss. It will shudder and jerk, and has started getting worse. I have scanned it several times and no trouble codes have showed up. I did pull the Diagnostic Data off of the engine with my scan tool, but I have no idea how to read it. It is not showing ANY trouble codes either current or pending. Some of the data points it recorded are showing out of the limits, but when I printed them out, these data items did not show up. I will try to type them here:

PURGE FLOW MON
Test $C5
Module $00
MAX: 1033.75PA
MEAS: 11264.00PA
MIN: 32.75PA

HO2 Sen B1S1
TEST: $D3
Module $00
MAX: 45.321
MEAS: 30.974
MIN: 36.335

HO2 Sen B1S2
Test $D3
Module $00
MAX: 45.321
MEAS: 6.910
MIN: 39.407

HO2 Sen B2S1
Test $D3
Module $00
MAX: 45.321
MEAS: 58.878
MIN: 36.335

HO2 Sen BS2

Test $D3
Module $00
MAX: 45.321
MEAS: 45.311
MIN: 39.407

Misfire Cyl 1
EWMA Misfire Cnt

MEAS 0

Misfire Cnt Last

MEAS 2

Misfire Cyl 2

EMWA Misfire Cnt

MEAS 0

Misfire Cnt Last

MEAS 1

CYL 3, EMWA 0 Last 4

Cyl 4; EMWA 0 Last 1

Cyl 5; EWMA 0, Last 1

Cyl 6; EWMA 0, Last 2

Cyl 7; EWMA 0, Last 0

Cyl 8: EWMA 0, Last 0


I can copy and post the rest of the data if needed. I just did not want to flood the thread with data if it is not needed.

Any ideas? Any other information needed? I have changed the spark plugs, and ran 2 cans of seafoam through it. Also I am running 100% 87 octane fuel at this time.