kmpconley

1998 F-150 4.2L will idle great in park or in Neutral. The second It gets shifted into gear (Drive or Reverse), the motor shakes like a SOB. Codes were read as P0303 and P1506. Both codes showed up twice for a total of 4 codes.

Check Engine light also flashes periodically, and I was told it's blinks when raw unburned fuel is passing through, and dumping down on the cats.

Any ideas?

kd4gij

The 0303 is cyl 3 misfire. And here is info on p1506.
http://engine-codes.com/p1506_ford.html

ToTheBar

I've had similar issues. Sometimes on a cold start it will shake badly for a few seconds. Check ur coil pack and wires make sure there's no cracks. The connections on the coil pack are poorly designed too make sure there on properly

kmpconley

We were told to check the IAC by unplugging it while running. Once we did that, nothing changed so we were told it's bad. Once we replaced it, problem was still there. I've checked all wires and connections, and seem to be good there. The guy that it was purchased from sai he just replaced the coil and it looks to be brand new, however I've delt with AutoZone electrical parts before and "new" don't always mean "good" or properly working. My question is, does it seem like the coil is still the problem? Cuz to me, that's the usual suspect.