Hoping for some help.99 f150 4.2 v6.Truck has been to ford dealer.They replaced plugs and wires.The truck has also been to another shop twice but i still get the code.I have replaced the coil pack and done a test on the egr valve as suggested on this forum
which tested fine.The one shop say if the use a little propane the engine smooths out.The miss is the worst at cold start time but
is there all the time.Once in a while i will get a backfire from the
engine compartment.If you remove the plug cables from the coil pack one at a time the number one coil seems to be firing a lot stronger that the others.Any ideas?

Ron