Here's a vacuum diagram. There is also a vacuum line going into the driver's side fenderwell for the cruise control if you have it. (Speed Control Servo in the diagram)
do you guys no witch line would most likly cause lean condition and loss of power at wot .or could any of them cause that i dont hear any hissing sound under the hood i am going to bring home my tethis scope to hear better .the codes are 172 and 176 i bought 2 new 02 sensors just want to make sure there is no vacuume leak cause that would set the same code right lean ??
Lean codes can definitely be the result of a vac leak (or fuel starvation, bad MAF, bad sensory input from other devices, etc). A lack of fuel pressure or MAF issue can REALLY rear their head at WOT.
IIRC, you are going to do some vac testing to watch for a drop after sustained constant RPM's (checking exhaust restriction). Since you will have the gauge hooked up: In general, look for about 20" hg of vac at idle.