Overdrive light has been flashing. Had it checked and was throwing code 0781 1 to 2 shift error I think. What needs to be replaced to fix this?? My truck has been running like crap after it warms up but only when it is in gear. seems like the engine is missing and cutting out, but when I was stopped at a light and it started cutting out I put it in neutral and it began running smooth as could be. Thanks in advance for any help.

 

Codes do not mean to replace anything. They only tell you where to start your diagnosis. That fault can be set if the trans is fragged, or if there's a nick in a tiny wire between the PCM & the trans.

The only thing you can replace & be SURE to get rid of that fault is the truck.

 

We had a 90's Chevy Cavalier at the shop with a similar problem found out the torque convertor was stuck in the lock up mode and acted like a stick shift car where you dont get on the clutch and its still in gear and dies. Maybe that can help you out otherwise probably a 1 to 2 gear shift solenoid. What does the trans fluid look like.