2003 5.3 - Low RPM Miss

[AnimalMother]

I've got a 2003 5.3 w/ BTR Stage 4 cam swapped into my 71 C10 utilize a Terminator Max wiring harness. The truck has run flawlessly for 6 months, but recently has developed a low RPM stumble that I cannot pinpoint. From idle to about 2,000 RPM it has a rough idle/stumble but as soon as I get above that it smooths out and runs perfectly. I've replaced coils, wires, plugs, injectors, fuel pressure regulator, checked all grounds, fuses, and all connections and nothing seems to change, and the truck smells as if it's running rich. Next up is the O2 sensor, but hoping someone else may have an idea/solution. Appreciate any help you can provide.

[hewittca]

It sounds like you are hitting it in all the right places to try and diagnose the issue. With the knowledge that it was running great but has now developed this issue, that rules out that there is any real problem with the swap itself. I think looking into the O2 sensors is a good next step. I would also check that you have the correct fuel pressure if you can. Please keep us up to date and what you figure out. These types of threads are always very helpful for anyone who has similar issues in the future!

[bigdaddy4x4]

check the mas air flow sensor

[LS short box]

Just thought. Over on LS1tech.com there is guy that does remote tuning on Holley stuff.
Search Andrewb on the conversions forum.