Need advise, unstable idle now a code
 

I have a 2000 tahoe with the 5.3 4wd with 175k miles. It started a couple months ago, intermittantly running unstable when first started. Alomost like it was running out of fuel but after about 5-10 seconds cleared up and was fine. Now we have our first cold morning of the year( below 28 degrees) and for the first time I got a service engine soon light. I pulled the code at the auto parts store and it was a p0171, bank one lean. They told me to replace the 02 sensor but the guy didn't seem to sure about that. Could these two problems be related? What should I check first? Any info at all would be greatly appreciated.

I have checked fuel pressure and it remains stable. I replaced the fuel pump approx 8 months ago.

Thanks
Angus

Angus,

It sounds to me like you may have some carbon build up in a few areas. When was the last time you change your spark plugs and airfilter? A cheap and easy way to clean carbon build up from your engine, crankcase, and fuel injectors is seafoam. I recently recieved a check engine light on one of my vehicles, they told me I needed an O2 sensor and catalitic converter ($1000) man hours not included. I bought two bottles of seafoam ($20). Added half of a cand to the gas tank, to clean the injectors, half to the oil, and about a little more than .25 to the crankcase. I drove my vehicle for about to days, drained the oil, put in premium fuel and the check engine light went out after two or three days. I still run 87 octane and no check engine light. Seafoam saved me $980. You can review the actual processes on youtube, just type in seafoam and do a search. if you add it to your oil do not drive over 60 miles before changing it. It can damageyour engine, if proper procedures are not followed. I use it all my vehicles. I hope this helps.