Q: Truck running rough

Hello. If this only occurs when the engine is cold then you may have a sensor reading incorrectly or you may have a vacuum leak. Most of the time if the Check Engine Light is on I start by scanning the computer for codes. This will assist me in finding what the computer is seeing. I will usually check all of the sensor readings to see if any are failing. If nothing is found from there then I start by cleaning the throttle body. If the throttle body is dirty then this will occur. If that does not help then the compression needs to be checked as a slightly leaking valve seat will also cause this. If you want to have this looked at, consider YourMechanic, as a certified mechanic can come to your home to diagnose your rough running condition and help you make an accurate repair.