Irregular readings EHA and Oxygen sensor

[904Matic]

I am sorry if i am repeating what someone else asked but i've looked through 50 posts and have not seen a answer yet.

The car is a 1990 300E 4matic, i was trying to read the mA to the EHA with ign. on the other day and it showed 18.78mA spec should be 20mA. But while the car idles it seems to stay around 0 to +1.5mA but never goes negative. So once i saw that i decided to test the oxygen sensor and the volts fluctuates all over the place. Also while WOT i only get about 8.78mV never goes full rich. I have checked for codes and none have come up as well. Is this a sign of the eha being off spec i tested the ohms and its within spec 19.5ohms and no leaks. Oh and yes i have checked for vaccum leaks and repaired a few in the car but from here can't find anything else.