Stalling

If the engine at this point is stalling, does it restart and stall time after time?

We need to start by finding out if this is fuel or spark. It sounds like your ignition is just cutting off. If this is the case, then we need to suspect the crank sensor or possibly the ASD that you replaced is faulty.

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

Let's go to the ASD and jump the relay and see if the engine will stay running. If it does, then the relay is the issue, or the ECM is not seeing something and shutting the engine off.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know what you find with this, and we can go from there.

Thanks

Okay, I will try to jump the ASD relay. Also, I checked the voltage to one of the plug-in harness to the ECM and one side was only getting 5.5 Volts. The only side was getting 12.5 volts. my question is what Voltage should my ECM get receiving?

Yes, the truck stalls and then restarts from time to time. also, I forgot to ask if I Upgraded my motor from a 5.2 to the 5.9 do I need to change the harness to fit the 5.9? The mechanic I originally took it to do the motor upgrade said no but also said that I don't need to do a 5.9 ECM and that it is the cluster causing my truck to shut off and stall.

Okay. Just to clarify when you say "time to time" do you mean it does this sometimes/intermittently and the other times it starts and runs normally? Or does it start and stall each time you start it, and it will do it over and over no matter how many times you try to start it?

From what I can tell it looks like the harness is the same, but I have not gone wire by wire. I am sure the connectors are the same but what I am not sure is that if some wires are in different cavities. However, I seem to remember that they are the same because I had a 1998 Sport that I looked to put a 5.9L in as well. I never did it, but a harness was not on my list.

What I suggest we do at this point is check for codes and make sure we don't have any. The cluster could be causing the issue, but I would expect you to have codes or at least the No Bus message in the cluster.

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

If we don't have any codes, then we can dig further into the harness.

It doesn't really stall anymore. the problem I'm having is, I can drive my truck but once I cut it off it won't start again until the engine cools down. like yesterday I used the truck to run some errands I cut the truck off for a few minutes when I got home, and it would start, I waited like a few hours and the truck turned right over once the truck cools down it turns on and runs great.

Okay. That is going to be a different issue than a stalling issue so we are going to have to get a new post started because others will not find the solution to this under this post.

However, this sounds like a crank sensor issue. So, check this guide out and get a new post started with what you find with this:

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

Thanks