Sounds like what happens when O2 sensor fails. Ecu never sees the sensor warm up so leaves mixture rich and mpg goes down. They can be tested. May also need to check connection for deterioration. 

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> On Mar 22, 2019, at 9:36 AM, Dan N <dn92610@gmail.com> wrote:
> 
> hi all,
> 
> 1990 tintop 2.1 WBX seems running rich and low mpg. Fresh tune up - spark
> plugs, dist. cap and rotor, new Temp2 sensor, vacuum lines checked,
> throttle body clicking right, fresh air filter and fuel filter, new coil,
> swapped in a known good used AFM but still running rich... running good no
> hesitation or stumbling, good idle @ 900 rpm, coolant gauge needle just
> under the red dot.
> 
> so the questions are:
> 
> - is there a problem with the injectors? should I get new ones?
> - is there adjustment somewhere to do? ie. adjusting the AFM?
> 
> thanks in advance
> 
> dan