Problem never caused the check engine light to come on therefore no code. I would run the van until it burned all the moisture off (didn't know where it was getting in). We put ie electrical grease on ignition module, coils and plugs.but the problem remained. It finally backfired like a bomb in Jan of 2017, after two years of this problem and blew a hole in my muffler. My mechanic suggested we check the computer for moisture. Sure enough we saw evidence where it was getting past the seals. We dried it out with a blow dryer and then liberally applied the ie electrical grease to the row of pin looking connections (there were two of these). Then we checked the circuit board and found moisture around that seal.We replaced both seals. Haven't had anymore backfiring or shuddering even though it has rained twice since our repairs. btw The computer for a 2005 is in a plastic box to the rt of the air filter. Glad to have it fixed. Van now has 269,000 miles and counting. One other issue I had was the return line on power steering con't to leak. My mechanic replaced the steel return line it with a rubber one. It's not high pressure so you can do it with that one.