The surging I'm referring to is the ECM fuel cutoff when the brake is applied.

 

Could you have a crack in your intake tubing? Somewhere there is a big leak.

 

coolant temp sensor for the ecu?

 

coolant temp sensor for the ecu?

It's the only way the ECU knows at what temperature the engine is operating.
Once the ECU knows that; it controls, timing, idle, injector pulse length, etc.
It and the o2 sensor are probably the 2 sensors that the ECU relies on the most to set the parameters for proper engine operation.

 

ok update i got the idle smoothed out now. I think it was the IACV, yesterday was the first full day with it, it did it in the morning and then was great on the way home. Today idle was good all morning, I am wondering if the IAC need to break in or something. So far so good.

I have a new coolant temp sensor I am going to install once my new throttle body comes in and is cleaned up and done right, I will throw that in.

I thought about the intake being cracked, but now I have had two consistant days with the idle back a 900rpm, I think I figured the problem out.

 

Since it is coming and going I would think you just have air in the coolent system, or worst case your head gasket is going and you are pumping air into the system (I have had this happen). Run the truck for a long time with the rad cap off to make sure that the air is out. Since you had the IACV off it may be having a hard time getting the air out. These engines are know for air everywhere.

 

Good point, I will burp it tonight when I get there. I think my radiator cap is bad also, it gets tight but doesnt lock.