I have a 2003 dodge ram 2500 diesel 5.9L. When the outside temp. 35 or lower my truck will not start,but if i plug it in and let it stay for about an hour it starts fine. Do you think the intake heater is going bad?

 

That problem is normally caused by one or more failing injector.

Many people have no starting issues with grid heater deletes into the teens or colder.

 

The question is when it does start, what color is the smoke if any?

 

White is usually an injector issue. If you suspect an injector issue, watch very closely at your oil level and check often the oil for a diesel smell... your injector may be dumpimg fuel and deluting your engine oil. Not a good thing