Problem with pickup

[Guffinator]

03 Mazda B4000 (Ford Ranger) with 4.0 V6.

My check engine light came on so I stopped at Autozone to get it scanned. It was reading 'left bank lean'. Cleared the light but it came back on a mile down the road. I figured maybe it was time for a tune up. Now the idle is wacky. The truck drives fine but when I come to a stop the idle gets really rough, it doesn't die but acts like it wants to. The rough idle seems to come and go as sometimes it idles just fine. When the idle gets rough however, if you give it some gas it clears right up.

Any ideas?

[FE_rex]

One bank lean is usually a vacuum leak or bad O2. I vote for vacuum. Any hoses, etc come off that bank that might be cracked etc?

[Saleen91]

I had the same problem after changing the plugs on Liz's expy. It turns out I knocked the PCV valve out of the valve cover. Check for something simple before spending the money.

[red95gts]

I assume you have two O2 sensors (one per bank)? If so, and assuming the connectors and wire lengths are the same, swap the sensors and see if the code follows the sensor or not.

But, look for vac leaks first...