I changed my plugs on my 2001, 5.4L SuperDuty two weeks ago. The original plugs had 62,000 miles on them. I replaced them with MotorCraft double-platinums. Everything took about 4 hours. Put anti-seize on all plug threads, but I did not use any dialectic greasy when I re-installed the plug boots.

The past week or so I've had an intermittent problem. When excelerating (usually 2nd, 3rd or 4th gear) the engine seems to be missing (kind of chugging but no sounds). When I let up on the gas a couple of times and re-accelerate, the problem goes away. I can go a couple of days without any such thing happening.

What do you think the problem is?

1. Bad gas ( I just replaced the fuel filter Friday and I had the missing happen again yesterday for about 10 seconds). I filled up about a half a tankful yesterday to see if it helps.
2. Plug not seated properly
3. Plug boot not seated properly
4. Bad coil over plug (COP)

Thanks for everyone's help.