I have a 99 with the 4.2V6 and 201,000 on it. Last year it started missing bad and losing power. I had a shop replace the plug wires and that helped. About a month ago it was missing again, I suspected the coil but a guy at the FNAP store said check the spark plugs. I did and they were really burned away, in fact I have never seen plugs so badly arched off on the ends? I put in new high milage plugs and that helped. But a slight miss returned, about a week ago I put on a new coil pack from Auto Zone. It seemed to help for a few days. But this morning while excellerating from 4th to overdrive it seemed to lack power and I could feel a small intermitant missing again. I've read other posts about missing or hesitation and someone said change the fuel filter. A local shop changed mine a few years back along with replacing my fuel pump which quit working. I have those special tools for disconnecting the fuel lines to change the filter. I suspose I can do that? Anyone have any ideas? I don't have the OBD2 reader so I would have to take it to a shop to pull codes. Any advice would be appreciated. I've been wondering if I should look into having my engine overhauled. Or if it would be better to just try and get a newer truck? I love my F-150, all in all it has been super reliable and I'd hate to sell it. Thanks.

 

These motors don't like any plugs or wires that aren't motor craft I would try replacing them with motorcraft. You can go to AutoZone and they will pull your codes for free. To replace the fuel filter is easy.

 

X2. I just did the same thing. I have the same motor but on a 2002. Mine was missing when cold and every now and again when I was driving. I replaced the plugs w/Motorcraft Platinums (gap them at .054 as they are NOT gapped from the factory), coil and plugwires. The missing went away and my gas mileage seems to have improved.

Hope this helps

You also may want to try cleaning the MAF if you haven't done it before. Its easy DYI.

 

Yes thanks, my wires are motorcraft OEM ones. I know the plugs I just bought were the platinum ones, but I think they are Autolite which I've heard can cause issues? I just called Autozone and when I get home I'm going to pull one of my spark plugs to make sure what brand it is. If I have Autolites, I'll buy Motorcraft plugs and put those in. I live in California and I believe the local Autozones can't pull codes. Something about some state law where repair shops complained about parts stores causing them to loose business?

 

Also try cleaning your IAC and throttle body