02 running rough with SES light on

[whitecrystal1]

This is actually my buddy's truck it's a 2002 4wd Sport Trac with a 4.0. I forget what code it showed when it was read but it was pointed to a lean bank condition for both #1 and #2 02 sensors.

It has 125K miles on it with the original plugs. I just helped him change 4 of them so far but we still have two on the passanger side to finish. It started raining heavily so we couldn't finish. We found the old plugs to be gapped as much as .090. I would have thought that would cause a rich condition not lean

The truck didn't run any different even with four new plugs, but I did notice that it smoothed out and ran great when I unplugged the mas air flow sensor. Does that mean the maf is bad? We did look at the vacuum lines for leaks but we didn't notice any (visually without carb cleaner).

Any help would be appreciated, Thanks

 

[James909]

Since when you unplugged the MAF it ran better I would start there. I would try cleaning it. Just remove the 2 security torx screws and pull out the sensor. Spray it down with electrical connection cleaner until it looks clean. Do not touch it! Reinstall it and disconnect the battery for a few minutes and see if it runs better.

 

[whitecrystal1]

That didn't work.
I tried that the other day at work. He called me when he got home (10 mile drive) and said the truck ran great and the SES light stayed off... thought all was good until he drove it later that night. He said the SES light came on right after he started it (2nd drive cycle) and it was running bad again.

What else to check? Thanks