[mwebb]

Originally Posted by Burned

The three Mode 6 tests I failed and what they are

TID 04 CID 20 - Steady State catalyst test bank 1
TID 07 CID 0C - No EGR off-idle test MAF Out of range high/low
TID 07 CID 0D - EGR decel test

there it is again , i flagged it above
MAF sensor is out of range , may not be a bad MAF sensor .

a vacuum leak or clogged or restricted exhaust could flag MAF values as incorrect for conditions

EGR can not run if MAP is out of range as MAP is used for the EGR test
vacuum leak can affect MAP and MAF values .

what is intake vacuum at hot idle ?
should be 20 to 21" at seal level and more important needle must be steady smooth with zero flutter

your system may be in open loop as
Long Term Fuel trim can never be zero , LTFT should adjust total trim to keep STFT bouncing on zero , equal amounts above and below
your LTFT = 0 can not be in closed loop

did those MODE 6 tests fail ? or just not run ?
the ECM will never run a CAT test with a p0300