My friend has an 02 ford lariat. 5.4L
The engine idles fine but when you are going down the road it skips. When he is towing a boat he said it is so bad that it sounds like the engine is going to fall out from under the truck. He has taken it to 4 or 5 different mechanic shops and no one can find out what is wrong. they have hooked it up to computers but cannot find the problem. he has replaced plugs, fuel filters etc...... I know this is a stretch but has anyone ran in to a problem like this?

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Did it start skipping before or after the plugs were changed? Those engines are notorious for blowing a plug out of the head- the threads will begin to strip and it will lose compression before it finally strips completely out.Also, alot of people I've heard of have had Ford change their plugs and the dealership installed the wrong plugs. I think there must be a wrong part number in the syatem somewhere. If it isn't the plugs, I'd check for a broken vacuum hose or clogged catalytic converter.

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I think it was before the plugs were changed. I am having a hard time believing that after taking it to that many mechanics that they have not found the problem yet. thanks for the info

cheak the coil and electrical system i dont know about these new systemsbut the old ones with points bad coil would cause this.

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The newer Fords don't have coils or spark plug wires. They have coil packs,which is basically a seperate coil that attaches directly to each plug. It's all or nothing- they don't get weak, they go out altogether.

he has you started in the right direction. if all that checks good, and assuming there is no misfire or other codes i would check your mass airflow sensor. take it out and look at it closely. there is fine wires that get coated with junk especially if you dont change your airfilter enough.
GENTLY clean it off with brake cleaner or mass airflow cleaner. DO NOT use compressed air.

i have seen this in all vehicles especially fords where this will cause fits and not set a code.

good luck i hope this helps.

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Try changing the controll modual. I had an 1988 ford truck that I had the same problem with. The control modual in my truck was attached to the distributer and as it start to heat up it would have problems. It also might be your distributer too. Most Auto Parts can check the control modual to see if its bad or not, but again sometimes it has to be hot before you see a problem. I sold that truck awhile back, but If I recall right after I sold the truck I got a recall notice on the distributor and control modual units. Thinking back I think the recall was for the years 1988-2002. Again this is going back a few years but if I remember right there was a law suit because a few trucks had stalled on the Hwys and caused some accidents.

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Larry Lowell

might be a vacuum leak or something like.

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I drove a 2001 ford with a 5.4L for 5 1/2 yrs as a company truck. The company had 20 to 25 of these trucks on the road during that time and after they got up in the 100,000 mile range started having the same problems as you are describing. Took them to the Ford dealer several times and really never got them fixed. The Equipment Manager was ready to pull his hair out and wound up sending a guy to a training seminar on those engines, he returned and bought a bunch of coil packs. When we felt it missing or skipping - take it to the shop and figure out which coil pack was bad and drive until another one went bad. It was a regular thing to see a p/u truck in there everyday to get a new coil pack. There's a coil pack on each plug and if just one went bad, your running on seven cylinders. They finally just changed them all and stopped the craziness. A little over a year ago began rotating those trucks out and they were all still running pretty well when they sold them.[/b]

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LeRoy Sawyer
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may have two of spark plug wires crossed

did you find the problem yet?? i am definately not a ford man but these triton engine fords are some of the best. built as tough as a tractor engine even being ohc engines. they are tough to work on for most people but require maintence like everything. i have pulled original spark plugs out at a 120,000 miles. LOL. i have also fixed a lot of stripped out heads because of not replacing spark plugs.

not many electrical problems aside from coils and once in awhile maf sensor problems.

if i were you i would find a mechanic you know does good work and let them fix the problem. it will save a bunch of time and grief. not like the good old trucks anyone could wrench on. i am sorry everyone points and plug wires are a thing of the past.