I have been having issues with my Suburban...Originally, it was idling and running rough and having a misfire on bank 1...Had a P0300 code and P0420...took it to the shop and they could not figure out what was wrong...They swapped thet O2 sensors to see if the problem would follow the sensor and everything went away...Ran great for about a month...

It started idling and running rough again...Now I have both the codes back plus the P0756 code...I replaced both O2 sensors and it is now running even worse...There is a strong smell of fuel at the exhaust like I am dumping to much fuel...

Any suggestions on where to start...Just like most, money is very tight so I need to try to do this mostly on my own...I have a friend that is pretty mechanically incline that can help me some...

Thanks in advance...

 

Welcome to the forum.

Since swapping the O2 sensors seemed to fix the problem, albeit for a short period, I'd suspect a wiring or connector problem. Worth checking.

 

Thanks for the reply...

I checked the connections again...They seem fine...

Wierd thing is, I drove it home yesterday, and once I got on the highway, it started running smooth...Ran good for about 20 minutes then starting acting funny again...When it acts funny, my instant fuel readings go down to 4-5 mpg...Like it is dumping way to much fuel...

Any other suggestions...

Thanks again...