Guys, 


Need some help diagnosing a rough running problem with my truck. Here's the timeline of events: 


1) Got an engine light and error code for drivers side O2 sensor, replaced sensor. Got the same code again, replaced the cat this time.

2) When leaving muffler shop, the truck started running really rough. Took back to shop, they ran the codes and it had a random misfire code. Shop suggested changing plugs and wires. 

3) Plugs and wire had 170K on them, so changed both, along with EGR valve. Still ran rough with random misfire code. But, now was popping out the exhaust. Random pops out the exchaust while driving.

4) Pulled pass side valve cover, everything looked good, there did not appear to be any issues with valve springs, rockers, pushrods etc. Everything worked fine when rotating the engine. The rough running smoothed out under acceleration and it ran fine. So, thought it must be an ignition issue.

5) Changed out coil packs. Truck drove fine, no more rough running, but was getting P0141 and P0161 O2 sensor codes. 

6) Changed out all four O2 sensors. Drove about 40 miles and the engine light came back on with the same codes. P0141 and P0161.

7) O2 sensor fuse checked out ok. Ordered 2 downstream replacement sensors and replaced. Drove 20 miles and engine light came back on with same codes. P0141 and P0161. 


So, any ideas on what might be wrong here? Would appreciate any advice! 


Thanks!