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Showing results for tags 'Air/fuel'.
Hello all. I have a 2013 silverado w/5.3l flex vin 7. Basically has rough idle in park and drive. Very poor acceleration. Almost seems to bog down when trying to accelerate. It will occasionally surge and for just a split second I can feel a bit of power. Also doesn't want to downshift when I lean on the gas pretty heavy. I've got to do near floor it to get it to down ****** and when it does it will drop down 2 gears a lot of the time. No engine light and it won't set any codes. Showed 0 misfires on all cylinders. Long Fuel trims usually in single digits negs. Fuel pressure 43-46psi at idle and highway. I've replaced throttle position sensor, Accelerator pedal position sensor, manifold pressure sensor, mass air sensor, plugs, coolant temp sensor, oxygen sensors. Fuel pump, intake manifold gaskets twice (now with "updated" steel gaskets), throttle body gasket/seal, injector o-rings (upper and lower). Tested all coils for strong spark. Smoke tested for vac leaks along with propane. It has never failed to start or even had a long start and has never died/stalled. I'm just kinda at a loss at this point. Any help will be appreciated and possibly considered. Thanks