I would inspect and test the igntion system (spark) first before anything else because it seems to be running just not well so I wouldn't suspect fuel at this time.
Pull spark plug out and make sure they're not worn or black & wet looking. Next check the resistance of each spark plug wire. For every foot of wire should be 1000ohms or 1.0kohms. Wiggle the spark plug wire while testing to check for any breaks in the wire. Next is the distributor cap and rotor. Inspect for any carbon trails where spark is leak or shorting to ground bypassing the spark plug.
These parts are fairly inexpensive to replace on GM products and are considered maintenance items.
It looks like you have a scanner to read the data the vehicle's computer is seeing. Can you provide the short term and long term fuel trims (abbv. LTFT & STFT). If not then the oxygen voltages (both driver side and pass side oxygen sensors if equipped with more than two).
Hope this helps and let me know what you find before you go spend money on tools.
Thursday, June 12th, 2014 AT 1:53 PM