Like many of you I developed a miss fire in my 2001 MPV. I followed all of the recommendations... before finally fixing the issue.
1. New Plugs
2. New Plug Wires
3. New Coil Pack
4. New PCV Hose
5. Sea Foam in the gas tank
6. Clean Throttle Body and Mass Airflow Sensor

All of this seemed to make improvements (at least in my mind for a short time).. but it really did not fix the problem.. and it would just come back in a day or so. What a frustrating issue. I checked for vacuum leaks, broken wires.. anything I could think of. Well finally I discovered my issue.

I had replaced the spark plugs 3 times in this vehicle... once around 50k, again around 80k and the last time around 105k. The last two times I replaced them because of the small miss fires I was getting at idle. It did not seem to do it when at speed, only at idle. Then at about 110k it start to get worse.. sometimes at speed. That is when I replaced the coil pack, wires, etc... Unfortunately it did not fix the problem... soooo frustrating.

Then I came across a posting on MVPClub site listing the specs on the engine. It showed the factory plugs and plug gap. Well I had replaced my plugs with Autolite Platinum plugs (AP 764) and the book at the auto parts store and the discount store both showed something like .040 as the proper gap, of which the plugs were already gapped at out of the box. Well the MPVClub posting showed the proper gap at .053-.055. So on a whim I re-gapped the plugs... and unbelievably it fixed the problem. No more miss-fires... at idle or speed. So give it a try... check the gap on your plugs.. BTW.. with the smaller gap I would get fewer miss fires if I ran premium fuel... but with the larger gap I run ok on the lower octane.