I went out driving today and after half an hour or so I noticed that my AF gauge read below 10:1 (off the scale). The thing is that this only happens when I have no acceleration or deceleration, as soon as I just barely touch the gas pedal the AFR goes to around 14.7:1 where it should be. Else I need to totally let off the throttle for the injectors to close and get that AFR up from the bottomless pit that it is in.
Any ideas what suddenly may cause this?