I changed spark plugs on a friends 2000 Honda Odyssey and he told me the next day he had to take it out and it was idling rough and shuddering. I thought there might be a bad spark plug or maybe I didn't gap something right. I pulled the plugs checked the gap and everything appeared to be fine. Gap is supposed to be .044, I did see a couple that were more like .041. test drove it and had the same problems. I ended up just replacing all of the plugs, just because I didn't really have time to mess around looking for a bad plug. First set I bought was Bosch platinums, second set was bosch Fusion (the iridium ones). still had the same problem, only actually seemed worse.

I read the codes at this point and had cylinders 1-5 misfiring and a generic random or multiple cylinder misfire. also I am getting a code for the EGR, but I knew that before I started, that's the next project.

I went ahead and put ngk double platinum plugs on next, because that's what I was told was stock. I know that probably was stupid, but I was just hoping something strange was going on and this would work.

Not sure what else to do now, no problems before I started, he just wanted to change them for a tuneup. I don't know how far he drove the vehicle after the first spark plug change, is it possible he damaged something when he drove it, and if so what? seems strange that 5 ignition coils would go, but don't know if the cylinder misfire could have caused this. Any ideas?