2004 silverado 4.3. My check engine light is on and scanner says 0174 and 0171 codes. also triggered a misfire alert and left and right upstream o2 sensors. replaced both sensors, the maf sensor, pcv and fuel filter. still same issue. sluggish start but seems to idle fine. looses power when starting off and under load but not all the time. it's very intermittent. I can't seem to find any vaccume leaks but have not done a smoke test, just some water around the intake manifold and get no indication of a leak. I know fuel pumps in these can be "lazy" but i need to get a fuel pressure gauge to test it. Just looking for anyones best guess as to next step. fuel pumps are upwards of 300 bucks and manifold gaskets gives me a significant down time as i do all work myself and by no means have an adequate garage to work out of and my wife never leaves me alone. this truck is my livelyhood and i need to expedite this repair.
thanks for any help you guys can give me