rough idle. smooths out with higher rpm.multiple cylinders misfiring.

What is your question?

scanned and came up with p0300 and p0404.performed in line spark test and replaced coil pack with no change.egr valve making faint exaust popping like exaust leak.ruled out crank sensor since it does start.80% sure its egr valve but haven't ruled out cat converter.150,000 miles so either is possible. will the p0404 code determine if converter is plugged?i need help deciding since neither is cheap.keep getting mixed opinions.