2.3 Ranger runs rich
My1985 2.3 Ranger pumps out clouds of unburnt fuel , runs rough and doesn't idle. The code reader does not push out any codes in key on position and only cylinder# code(4) with engine running.When reader is activated, revs increase and mixture becomes more rich. I suspect some kind of mixture control sensor, but where to start?.New injectors and plugs were fitted as well as plug wires. O2 sensor is difficult to remove . I'm in the Bahamas so any help would be welcome.