If you have a matched set of N210H injectors and a good o2 sensor, the ECU may be able to adjust the fuel trim in closed loop - or it may not be able to do it - I don't know. But - there's nothing it can do when the engine is cold, so you'll be seeing extra fuel in the cylinders. The downside is oil dilution, engine wear and maybe catalytic converter damage.... not to mention poor fuel mileage.

The problem with using a mis-matched set of injectors is an unbalanced fuel supply being read by only one o2 sensor. With a mis-match, even if the o2 sensor adjusts the overall mixture to average a correct overall average mixture, some cylinders will be lean and others will be rich.... a prescription for a blown engine due to oil dilution in the rich ones and detonation in the lean ones.

Whatever injectors you use, I'd recommend a set of the same identification numbers. My preference for the Montero 3.0L SOHC would be the B210H/INP-051.

Are you sure you have a Montero engine in the truck? It's possible someone could have swapped in a Diamante SOHC 10:1 CR block.

Frank