smoke from o2 sensor

[jcmandia]

have a 1994 lwb. stalled on me a couple times and seemed like it was an issue with fuel getting to engine as idle went up and down and stepping on gas did nothing. Felt like gas delivery was cut off. It restared right away both times. I then added a fuel injection cleaner to next tank. Truck ran well for about 20 miles then started to stutter, lacked accelleration and backfired a few times. I changed the plugs this morning as been meaning to do so and thought it might help. Gaps of plugs removed were below spec (about .025 in) and plugs were dirty so thought that may have been issue. After i changed them i started truck and let idel for about 2-3 minutes with bonnet open. Engine now sounded ok but did not test drive yet as smoke started coming from O2 sensor on passenger side No smoke from driver side). May have been burning off some rogue lubricant but i cleaned and restarted and it smoked again.

Any thoughts on smoke from O2 sensor or sudden misfire/backfires (i was thinking cleaner did not agree with engine or bad mix ratio with gas). Thanks

[jcmandia]

I cleaned the mass air flow sensor and now seems to be running strong again. Led to this as when sensor wires were disconnected engine would run normal and then when plugged back in back to issues. Never registered any warning lights even when driving with sensor disconnected so guess this is another issue to look into. I will update in a couple of days if not solved by this.