90 k5100 code 44 lean fuel

I did some searching and found some info but could the o2 sensor be the problem? The truck idle is not very good the biggest problem is when i try to acclerate hard it boggs down and just want go for a few secs and then pick up. I also read it may be the MAP sensor, but the MAP is new. It has a new fuel filter I rebuilt the TBI (it idles hella better now), plugs wires cap and rotor all new. If i have a vaccum leak I can't find it I tried the hose to the ear method and the starting fluid method. I put a pressure guage on the fuel line and it was good but the way I had the guage hooked up was shady. Is their anything I'm missing? could the o2 sensor really be causing lean condition? thanks for your help,
Tommy

I assume you mean K1500. I have to factory manuals for 1990 and Code 44 diagnostics call for checking:

- O2 Sensor Wire
- O2 Sensor ground
- Fuel Pressure within specs
- Fuel contamination

If all check OK, the 02 sensor is faulty.

//2000CAYukon

The symptoms you describe are classic of an O2 sensor with a sluggish response. See here (http://www.angelfire.com/wa3/mechsoldier/o2.html) for instructions on actually testing this sensor if you'd like.

Thanks for the reply guys. I'm going to get a new O2 sensor tomorrow. I'll reply with an update afterwards.
Tommy