98 with a 4.6. Anyone else have intermittent rough idle on start up which is accompanied by a smelly smoke. This goes away after driving about 1/2 mile. Dealer says it is gasoline volatility, however it has only done it about 5 times in the last 2.5 years and may do it once during a tank and not again.

 

Harley

I have a 99 with a 5.4L. When I first got it I ran 93 Octane. It idled a little rough so I started using 89 Octane and finally switched to 87 Octane. It runs much better on 87 Octane. Don't know if this applies to you but it helped me.

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1999 F150 Extended Cab Short Bed 4x4 Deep Wedgewood Clearcoat, 5.4L, Off-Road Package, Towing Package, 3.73 Limited Slip, Carpet Delete, Electronic 4x4 Shift (mistake), Sliding Rear Window.

Modifications:
K&N FIPK
Uniden Beartracker Scanner
Maxon CB
DeeZee Toolbox
Hi-Lift Jack
2 Bed mounted 12V Outlets
Dixie Air-horn
Lund Bug Deflector

 

Good point-I have always used 87 octane and the dealership mentioned that you should not use the higher octane gasoline.

I am not sure what the difference is (I sell gasoline for a living) as the volatility of the different grades is the same. In fact the truck runs great on 89 octane made with etahnol which is actually higher vapor pressure. Thanks for the comments