depends on what you check on the amm with the meter.

best way to check them is on the car and a digital volt meter.

key on, engine off-1.4v
idle-2.3v
4k-4.0v

measure this at pin 3 on the amm.

that being said, when the amm fails, it, in my experience, ALWAYS fails lean, not rich. a bad fuel pressure reg. i have seen before, driving the pressure up, causing the problem. they don't always fail by leaking into the intake. once you fix it, pull the fuse next to the battery. this will clear the code and reset the adaptation so the ecu doesn't have to readjust the mixture setting it remembers. good luck, chuck.