Need suggestions 2003 yukon 5.3
initially these codes came up
po101
po171
po220
po300
Checked throttle body harness...ok
Cleaned throttle body
ran fuel cleaner through
changed o2 sensors
changed fuel filter
changed air filter
Checked ground wires
Reduce Engine Power light still comes on and goes to limp mode
Also note RPM's bouces 500 to 1000 at idle
only codes now are
po171
po174
Suggestions?