Chevrolet Repair: 1993 k1500 4x4 running horrible, fuel pump filter, vacuum leak

Question
1993 k1500 4x4 5.7L TBI idles alittle rough and hesitates bad during acceleration, i get a code 44 lean exhaust but clears on next startup. it has a new o2 sensor, fuel pump,filter, injectors, fuel meter ass. in the tbi/w gasket, new tbi base gasket, plugs, wires, cap, rotor, ing. module and coil checked, tps and iac checked, vacuum lines checked and couldn't find a leak on manifold or tbi, and fuel pressure was checked and i know the knock sensor has been replaced at one time. when i got this truck it was in dire need of maintenance. this has thrown me for a loop and not sure what do check next i was thinking maybe the map sensor was sending a bad signal to the comp but I'm not sure. in need of help here buddy.

Answer
Only suggestion is take off oil cap and see if it is pulling excessive vacuum.  It sounds like you could have an internal vacuum leak in your intake.  Or possibly plugged intake passages not allowing the correct air flow.  Also you may want to replace your egr valve it could be opening too soon.