When I drive my truck for about 20 minutes, and it gets up to temperature the motor will sputter once or twice at a red light then will stop

This can happen when the throttle actuator gets dirty and needs to be serviced. Here is a generic guide to help you see wat you are in for and specific instructions in the diagrams below to show you on our car:

https://www.2carpros.com/articles/throttle-actuator-service

it can also be a vacuum leak which is common please, do this check when the engine is cold.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Check out the diagrams (below). Please let us know what happens.

Hey Ken, thanks for the great information. I forgot to mention that it is a diesel truck. I don’t know if that changes any of the diagnosis. I totally forgot to mention that in the first question.

You can still use the guides, but it sounds smore like the engine coolant sensor is shorting out. but we should run the codes first, here is a guide to follow, let me know what you come up with:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down this guide and report back.

No codes show up when the problems happen. That’s why I was a little stumped with this issue.

I would start by servicing the fuel filters; you could have water in the fuel. here is a video to help and instructions for your truck in the diagrams below:

https://youtu.be/6de-1mIpzi8

Check out the diagrams (below). Please let us know what happens.