Having some issues with 1601 box

Hi everyone i have searched through the forum for some solutions but i'm having a hard time finding help. I have a 92' 240sx with the SR20DET motor running the 1601 box with the stock CAS wheel. For some reason the tach in the car and the RPM on AEMpro is off. When the car is idling around 1500 rpm the AEMpro is showing around 800rpm. Is there an adjustment needed in order for this to read correct?

Next, the AEM is reading lower AFR's than my AEM external wide band gauge. It is set up to read gasoline but for some reason it still reads lower. I'm sure there is a fix but i'm new to the AEM so it's just a little puzzling. So far i was able to get the car to run and rev pretty clean. It drives ok but the rpm problem has me worried. So far i like the system and would like to get better at it. I almost gave up a few times but i came on here and got some helpfull info so now i'm excited about learning more. I will try to take one of the AEM tuning classes in the near future so I can get better at it. Any help would be appreciated. Thanks in advance.

Kev