1999 Ford F-150 Q&A

1999 Ford F-150 Question: after 20 to 30 miles my truck picks up a bad miss at lowend and overdrivw

missig bad after 20 miles or so a small miss otherwise only code evap leak but has been there before miss started -
Answer 1
poss alot of things do you have any eng codes? -
Answer 2
Also you can have a cylinder contribution test performed with a scanner, most likely an ignition coil or coils failing. -
Answer 3
From the description it sounds like you have a type-a ignition misfire, the threshold for setting dtcs on older fords is broader so they won't set a code as fast as a newer ford. You'll need to take it to a shop that has a power balance test capability that will show exactly which cylinder is misfiring to get an accurate diag. -