I just took my truck in for what I thought was a slipping clutch. Turned out to be a bad spark plug wire. Number 2 cyclinder. The tech told me the reason it didn't show the MIL was beacuse it was not constant. It only happened every once in awhile under load. Just FYI for all you V-6 guys.

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1998 Ford F150 4.2L V6
American Racing Rims
Brush Gaurd
Tinted Windows
Saving for lift and SuperChip
3.55 Rear
5 Spd.

 

I had the same problem except mine was way worse and more pronounced because I also had two clogged injectors. I have a temporary from a taurus while I wait on my Jacobs to get here!

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1999 F150 4x4 sport package,4.2 V6
planning lots of mods
So far:Panasonic in dash off road CD player, 85 watt driving lights, Yellow All Weather headlights 55 low 100 high, 55 watt driving lights on rear, added switch panel above radio (chrome!), added fuse box for new acc., floormats, Class III reciever, Y pack to dual 13" tips{great sound!}, clear sidemarkers, custom airbox mod(chrome), tinted windows, bridgestone duelers.
Working on twin turbos!

 

Same problem here. But mines relly only bad in the rain. But The carbon tracking is very visible on a couple of wires. But its kinda an awkward situation, its only a problem in the rain, so I never really think about it except when it rains. But I damn sure don't feel like working on my truck when its raining. So I haven't done any thing about it in a year.

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BigBunnell

98 F150 4X4 XLT flareside V6 5sp K&N Flowmaster and some other goodies

 

I have a '98 F150 4x2 4.2L with 5-speed manual trans. In October of 2000, I noticed a slight lurch feeling when pulling away from a stop. It felt to me like something in the rear suspension was bound up or seized and then released when I started to accelerate. It was more noticeable with weight in the truck. In early 2001, I started to feel it when driving up hills. I then started to think electrical problem. I took the truck to Ford and they did an electrical diagnosis ($178.00 Canadian) and found nothing. They told me that I should do an injector power flush. I didn't bother because I felt that they were only guessing. I took the truck to a well respected private garage and they replaced the spark plugs and cleaned the Mass Airflow Sensor. The problem was worse but it was now obvious that it only happened when the truck was at operating temperature. The private garage then replaced the spark plug wires and the problem was gone.

Lessons learned;
1) faulty plug wires may not show up on Fords diagnostic equipment.
2) faulty plug wires may not show up unless the vehicle is at operating temp's.
3) faulty plug wires may only show up under specific conditions such as high vehicle load or wide throttle openings and may be mistaken for other problems.

 

Mine had the exact same symptoms Glenn