My partner and I, recently bought and leased back a C172R with the 180 hp [airplains] mod and fuel injected.  The school grounded it for a rough running engine.  We (partner and I) said it's running rich, went out burned the plugs and it ran fine but had to have a shop look at it because being grounded.  The mechanic agreed newer models especially fuel injected run more rich. Plus, they typically stay low with schools.

Is there something out there: technique, mod, placard, etc that can addresses this propblem.

Thanks in advance