I have a 1997 Ford F250 HD with the 351W. I have suspected for sometime that the idle may be too high. It runs fine and gives me no issues at all. My only question is what is the proper idle range and how do I check it?

 

my truck idles around 800 rpm.....notr sure if thats proper range or not but i sounds good and doesnt fluctuate at all

 

I do not even know what RPM I idle at because my truck does not show me RPM at all which is the issue im having how do I determine the RPM.

 

The coolant temperature sensor can cause that. Also, vacuum leaks.