Chasing the same problem?
This thread has been really helpful. I have also been chasing a rough idle/running problem with my 2003 5.7. No codes. I have replaced the PCV valve, upstream O2 sensor, and intake manifold gaskets. I just changed plugs and only discovered a valve cover leak on the left side #5 cylinder (oil running down the plug from the top). None of this helped. The engine sometimes starts and runs seemingly fine but as soon as I step on the accelerator it bogs down and idles rough. If it sits for a while, it may start and run seemingly fine. If I accelerate slowly, it runs smooth but still seems to lack power. It all changes if I accelerate quickly. Going to pull the valve covers and inspect the springs this weekend. Does anyone else have any other suggestions? Also, where can I get a new set of springs for a decent price? Thanks.
Jason
