2007 Honda Odyssey 2007 Honda Odyssey Engine Problems

Dear Car Pros,

2 years ago we purchased a brand new 2007 honda odyssey. At about 9,500 miles we were on the highway when the engine began to jerk violently and the check engine light came on (according to our receipt, the dealer found engine codes p0301, p0302, p0304, p0300 if that helps). It was towed to the dealer we purchased it from. They called honda corporate where they were advised to completely replace both cylinder heads.

1 year later at 17,000 miles (on Christmas Eve of all days) we had just made a long trip to my visit my wife's family. When we arrived, the engine began to jerk again (like before with most of the same error codes). They found that our original dealer had been sloppy with the service and had not tightened the head bolts down in the front and had pinched the gasket in the back causing a very, very small oil leak. They also found that the misfiring was happening in cylinders 5 and 6. They checked the timing, replaced the head gasket and reset the codes. It appeared to be fixed and ran fine until last week.

Last week at almost 39,000 miles we were on our way to the airport and it happened a third time with the jerking and the check engine light. It was towed to a different dealer and they found the same error codes as before except this time it was only misfiring in the 4th cylinder. They checked everything that the previous dealers checked (compression, coils, spark plugs, connections) and then traced it to the PCM computer. They replaced the PCM and told us it was fixed. I asked the service manager if this could have been the problem all along and he said he wasn't sure.

In order to keep this short, I've left out all the details involving all the hassles we've endured with various dealers (the worst being the one we bought it from) and the frustration we have with our van. Honda did give us the extended warranty for free but I don't want an unreliable vehicle that breaks down every time we take a long trip, especially with Honda's reputation.

I don't understand how the PCM works but if the PCM was telling the engine to misfire since 9,500 miles, why did it show up at 17,000 and 39,000 miles? If the dealers reset the codes does that reset the PCM? In which case, why would the PCM decide later to misfire again? And now that we have a new PCM, does that mean it might do the same thing in another 10,000 miles?

So my question to you is, was it the PCM all along? Is it fixed for good now? Or is this something else?