Ok driving down the highway (80mph) yesterday My A/F droped from 13's to mid 10's-11's and started to run bad. I have a rough idle now and need to get my car to AAM for some tuning but my A/f never droped that low that fast any idea? After a few miles car started to run ok at the lower A/f

 

Could be a bad injector or coil.

 

Were you just cruising along when it happened? If so....a bad coil (lack of spark), will cause your AF ratio to drop...as Westpak mentioned.

Also interesting becuase at cruise, your AF ratio should be much closer to 14.7:1 or near that range...not mid 13's.

 

Talked to aAM today and they said something about a vacum line might have come off. sharif at cruise my A/F was in the 14 range before this. and yes I was on the highway got off and thats when the A/F droped. Ran real bad for a few miles then everything was ok but my A/F is till mid 10 to upper 11 right now. On highway its also the same doing 80mph am I still safe to drive? WOT is mid 11- mid 12's

 

running the FCON my A/F should still be the same just guage reading worng right?