Doing an Engine swap on 91 300 tt

Doing an engine swap on a 91 300 tt and have a snag. Motor turns over and tries to fire up. Have fire and fuel....Noticed one of the plugs (sensors) on the back of the head has been tweaked (damaged) What are these sensors and will it cause the issue I am dealing with. Also what years did the exh flange change?
Ok car is running.......but 3 of the injectors are not hitting......(two closest to front) on the drivers side and (one very front of motor) on the passenger side

Thanks for any help.

do you have a picture of the sensor you are talking about?