P0171 code on 1999 Chevrolet Malibu LS 3.1

[Gregory]

I have a 1999 Chevrolet Malibu LS with a 3.1 with a check engine code P0171 that's keeps coming on. I do not see any vacuum leaks or broken vacuum lines. I have replaced both Oxygen Sensors along with these other parts EGR Valve, Air Check Valve, Temp. Coolant Sensor and still get P0171 code. It also tells on the Snap On Scanner MT 2500 that it has random misfires. I need help on this problem Please help

[butch]

If you are getting a lean code P0171 and a misfire, then you could have the upper or lower intake manifold gaskets leaking vacuum or a split fuel injector O' ring. Spray some brake cleaner around them to see if the idle spikes.