Good afternoon All,

Finally i got new cats on my wife's 97 5.4L v8 4x4 expy, however i am getting codes p0174 and p0171 "system too lean on bank 1 and system too lean on bank 2.

I put a new MAF sensor & applied fuel injector cleaner into the tank, however this has not helped at all and engine is still missing...

I changed all 8 spark plugs about 3 weeks ago....

any ideas guys? it's like is loosing power .......and shuts off on me sometimes when i turn AC on.......

Also the pulley tentioner i know is bad cuz is making squicky noises......could that be part of the miss?

Again guys your help is much much appricated thanks a bunch!