Just want to start by saying and spent over an hour looking through all forms I have read probably at least 20 or more posts that just start exactly like this, but every one of them just ends without anybody telling their resolution to the same problem.

2004 about 140,000 mi. Previous owner allegedly replaced the coil packs and did a tune-up probably 4 or 5 years ago. Runs great and then it random it's suddenly has massive misfires and bleaking check engine. I'll push the gas pedal down it will struggle and then suddenly it will run good for 30 seconds and I'll go back into this misfire limp mode.
If misfire codes for two, four, six, eight and code for catalyst causing damaging multiple misfires.

No weird noises or smoke. I'll do a compression and leak down test but I can't imagine an intermittent problem with all four cylinders on one side has to do with a head gasket or compression. I've never heard of a head gasket blowing across all four cylinders at the exact same time.

At this point I am going to replace all four O2 sensors and both coil packs and relocate them at the same time. But I'd love if anybody else has seen the actual solution to this fairly common problem.

Thanks all.

 

The only component common to all cylinders on one bank that can cause misfires is the upstream oxygen sensor. No need to replace all four, especially not the downstream, post-cat sensors that have NOTHING to do with engine management.

I recommend buying your replacement O2 sensor locally. Too many stories on this forum about O2s being bad out of the box. Walker recommended, Bosch if you must.

 

Here is a trick, unplug the upstream 02 sensor. When this is done the ECU goes in to speed density mode and only uses the MAF and rpm for fueling, no 02 sensors. See if your misfire comes back in that condition.