So, after cleaning the TB and MAF, the symptoms have not changed. I have also sourced a new TB, and a new MAF sensor. With the new parts, I still have a 6 codes now, All codes are “bank 1 lean”. Intake gaskets are not leaking(after checking with smoke test), fuel pump is showing excellent pressure on the rail.
When I try to accelerate, I get a slight mis-fire until I reach 1200rpm, and then it smooths out. But, under hard acceleration, foot the floor per say, it has a stumble, a mis-fire, and after a few seconds, it’s almost like it “catches up”, and smooths out.
I have ran this truck with the same plugs I had in before I ran with a leaking head gaskets, which I would expect to foul the plugs, which could, in my opinion, cause the Mis fire?
I also did write down, my OEM thermostat was 161*, but they changed them to 181*. Ever since then, I’ve seemed to have more issues.
Does yours have the physical PCV valve at the back end of the valve cover, or is it integrated into the cover? If separate, check it for function.
This sounds a bit like a vacuum leak on the driver's side of the engine, with it being able to overcome the leak when the engine vacuum is low (higher RPMs). Or perhaps a lazy or dead upstream oxygen sensor. If you can switch the upstream O2 sensors side to side, you could see if the code moves to Bank 2.
When you say the fuel trims are good, what are they? Do you have values for both short- and long-term trims at idle, and at 2000 rpm to post? Not sure why you'd get a lean code if the trims are good.
I can try and recreate the issue, and get a freeze frame data log. It would show the value I believe at the time a check engine light occurs.
And I believe I do have the PCV on the back of the drivers valve cover. It is the newly designed or updated one GM calls for.
I’ll try and get some trim values today. It’s not too cold out today.