1998 f150 4.6L Just replaces coil pacs for 0307 code. Truck idles and revs fine slowly. If you try to rev fast shakes like it is missing. NO error codes showing.

 

i had the same problem at it was ignition coil 4 and 8 i replaced them and it was gone

 

Mountaindew,
Im having a bad misfire as well. You can take a look at my tread MisfireTroubleshooting 98 4.6L V8 . Mine came on very suddenly and was 0303 code. I swapped the coil packs(only 2 on my engine) as I was trying to get a code on a different cylinder....but no codes are appearing even though the engine is still running terribly (mostly under load, but I can still detect a misfire at idle. I just cleaned the MAF sensor but no change. Ive been running for about 3-4 days a few miles here and there, but no codes appearing.

 

replaced both coil pacs when 0307 cade came up. One was definetly bad and the other was going. I checked them with an ohm meter. Error code went away and it shows no pending codes. If I slowly press the accellerator the engine revs up fine to 3500 rpm. Push the pedal down faster the truck starts a slight miss and shakes. Idle sometimes is smooth sometimes a slight shake.