I have the same code, but with a 2001 Accord V6...it says 1399 multiple cylinder misfire...the guy at autozone showed me the probable causes and they were; EGR, valve adjustment, and coil ....I also have an OBD reader and it initially said that 3 cylinders were misfiring. I have replaced the plugs and purchased one coil to troubleshoot....the car is still running...but a little rough and the CEL is flashing. Now the code reader says 1399: multiple misfire. I dont think it would be running as well as it is if 3 cylinders were misfiring as the original OBD reader said. I have no trouble getting up to highway speed and it still seems to have plenty of power.

 

Do you know if the egr ports have ever been cleaned? There is a "kit" of sorts from Honda where you kind of enlarge the ports and install a pipe to try to prevent it from clogging again.....

 

When was the last time you replaced your spark plugs or wire? What brand are they?

I've had similar problems with cheaper Spark plugs and wires. The wires would "leak" right out of box.

Have you checked your spark plugs to see if there's any oil? If your valve cover gasket is leaking, you can get oil in the plugs and cause them to misfire.

 

I changed all the plugs yesterday--installed bosch iridiums....and the problem persisted...so I went and bought an OBD II. I initially got codes stating that I had misfiring in 3 cylinders and another stating random multiple misfires...code 1399....so I bought one coil pack and started exchanging the known good part one cylinder at a time. Luckily, the second one I checked was faulty....I know this because removing it didnt change the way the engine ran (rpm, ignition advance, sound...) So, I put the new coil on that cylinder and now the car runs great again and there are no codes....so far I have put about 100 miles on it and no problems...

 

Glad you found the problem. Congrats.