2006 Hummer H3

Noticed the Check Engine light would flash on during startup for a few seconds and how the engine would struggle a bit so I bought a FIXD scanner and plugged it in and received error codes P0014 and P0300. Turns out the engine is misfiring on startup. The two codes have been quite consistent as a pair each scan until last night when the Check Engine light when on and this time stood on. Now getting error code P0171 as well. Car feelin real sluggish at times and performance struggle becoming more noticeable each time. Is it looking like I'm going to have to replace the Camshaft Sensor? Or might there be more to the issue?

 

Greetings and welcome.

Any related work done to the engine?

While reading the code on your scanner, can you find a fuel trim reading for each code? It will be labeled something like "LTFT" and "STFT". If so, post those numbers (either a "+" or "-" percentage reading). Those are really helpful in diagnosing issue like this.

The P0171 supporting the idea of running lean, which seems related to your misfire. One way to check for vacuum leaks (common cause of lean condition) is to release a small amount of propane (with engine running) around PCV lines, air intake baffle, and intake manifold to see if the engine "revs" in response to the propane, meaning there is a vacuum leak sucking propane into the engine.

 

Clean your MAF with MAF cleaner, clean your TB with TB cleaner, make sure your air filter is in proper position in its filter box and when checking that replace if dirty.

How many miles on your spark plugs and are they ACDelco brand?