P0174 P0171 Reduced Power

[patriotsfanatic6]

i have a 04 Tahoe 5.3 AWD that has gone into reduced power mode probably 4 or 5 times in the last 1000 miles, it did it tonight and had codes 0174 0171 and 1516, the other day it had p0171 and p0174 while just idling but never went into reduced power, it seems everytime its lost power it has been on cruise control around 75-80mph at the start of a hill when it would want to down shift or start to increase rpms.

 

[jbb01]

Sounds like a lean condition...may want to check intake manifold gasket. Similar codes were thrown on mine but only when it was very cold outside. Changed the gasket and all is well now.