I took off the negative battery cable and plugged and unplugged the ecm cable and inspected the wiring.started up no check engine light .Used the key switching method and it did look like a code 12.I have a hard time with the flashing light thing.I reset the trip reading and drove it .At first it seemed fine up til it got 1.4 milesthen it started sputtering and backfiring thur the muffler this continued unti 2.0 miles and then it ran fine.This used to happen right away then when it got about .8 of a mile it would straighten out.I believe it did this before I replaced the coolant temp sensor .I was getting a code 22.

 

I had a similar issue with my 2003 VW Jetta. when cold, would sputter all over the place, but even out once the engine warmed up.

Turned out to be my ambient air temperature sensor. The wiring was buggered and once I repaired the wires, the issue went away.

Not sure if these trucks have anything like that since, but it's something worth thinking about.

 

Thanks it does have that sensor which I replaced .Wll check wiring.