i don't understand how you can even get a 5.9 AFR reading when the guage only displays between 10.1 and 20.1 AFR
and if you're getting reading below 10AFR then you have it adjusted for the wrong type of fuel
but what do i know i don't own that same AFR guage... it's just from a quick google search on the range the guage displays
hope you figure it out
YEah...something is up....The Autometer only goes down to 6:1.....which is what is may be doing....and you might have a bad sensor, unless you are flat out dumping fuel on WOT.