My truck has been in the shop 5 times now for the same problem. I don't have a code scanner but the check engine light comes on for several days/weeks then turns off for a day or two and comes back on. The dealer has done some rewiring and replaced the PCM. Now they are thinking that the PCM is bad again. They just replaced it two weeks ago.

The symptoms of the problem are a rough start first thing in the morning. By rough I mean high idle. It is usually around 12-1300 at first and then slowly climbs down. When driven cold the truck hesitates on acceleration. Some times there is shaky associated with the hesitation. The mechanic noted that he felt the "skip." I'm not very good with diagnosing problems on vehicles, would anyone know what might be causing this? Obviously my dealer needs all the input I can give! Thanks.

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'98 F150 XLT STX
Reg Cab Flareside
Oxford White
4.2 V6 auto

Mods:

• ARE LSII Lid w/Sport Wing
• AAD F1 Cobra Hood
• BodyGuard bedliner
• Bugflector
• WeatherGuard rain deflectors
• Nerf Bars
• Steel Horse Billet Grille
• Clear Corner Lenses
• Panasonic 600u Head Unit
• Panasonic 8 Disc Changer
• Cherwin Vega 6x8's in factory locations
• 40 Series Flowmaster exhaust Custom

 

Things I would check. In sequential order.

Oxygen sensor
Fuel Filter
Spark plug gaps
idle air control motor (or equivalent)
timing??

1200-1300 RPM is the usual cold start idle until fan is engaged or truck is put in gear. It should settle down right after that. Also if the gas cap is not on all the way the check engine light comes on (wife did that).

Only a best guess. Hope it helps.
I had this problem while it was still under warranty. When I find the paperwork I will let you know.

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1998 F-150 XLT Lariat 4.6L
Red/Black 2-tone

 

Talked to the dealer today. After having my truck for three days they have determined that they need to change the spark plugs and wiring. They told me cost would be 300+. I told them I thought this was warrantee work you never got right...They dropped to 100+ for parts...labor is on them.

Does this seem right? I thought it could be spark plugs if it was missing like it was, but wouldn't they have picked that up the first visit. I believe their first attempt(6 months ago) was to rewire.

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'98 F150 XLT STX
Reg Cab Flareside
Oxford White
4.2 V6 auto

Mods:

• ARE LSII Lid w/Sport Wing
• AAD F1 Cobra Hood
• BodyGuard bedliner
• Bugflector
• WeatherGuard rain deflectors
• Nerf Bars
• Steel Horse Billet Grille
• Clear Corner Lenses
• Panasonic 600u Head Unit
• Panasonic 8 Disc Changer
• Cherwin Vega 6x8's in factory locations
• 40 Series Flowmaster exhaust Custom