04 suburban, having random P0171 code and missfire

[Shatcher0428]

Good morning!!! Hey guys I am scratching my head on this one. I am getting a P0171 bank 1 and when it does it i get a missfire. It does not do it all the time. Does not happen whenever it first starts, just whenever I have driven it a good 30 miles or so. It may not do it every time either. When it does it lacks power and check engine light flashes. Since i have had it, I have replaced, fuel pressure regulator, fuel pump, both Front 02 sensors, new plugs and wires, new mass air flow sensor, does have a cold air intake, engine was rebuilt about 50k ago. i am scratching my head on this one. Any help would be appreciated. Ah also really noticable at idle, but if really get on it, its usually smoothes out after a few miles and quits doing it???? I am stumped.

 

[Fless]

Read and report your short- and long-term fuel trims, preferably both when it's good, and when it acts up. Could be a faulty injector, injector imbalance, or something else.

Any freeze frame data for when the CEL is/was flashing?

 

[rmaker]

I recently had same code - Bank 1 To Lean - it was a vacuum line that came undone on the left side of the intake, it has a 90 elbow on it. It wasn't throwing any misfires though. The one misfire code I did have (at a different time) was from the heater hose connector leaking onto power pack 8. To lean indicates to much air (obvs), check for cracked hoses/lines.

 

[Shatcher0428]

Thanks everyone! I put a new throttle body and replaced 02 sensor again and took care of po171 and the random misfire I was having