99 range 4x4 off road problems

when i go up my road it wont pull some times i used priemium gas and it did better. it ify on some starts idles super low and acts like it will stall. i have cleaned the fuel injectors and rplaced the oil. can the air fillter being dirty cause some of the problems?

any check engine lights on? new plugs?dirty air filter will definatlly cause poor performence.