I had to have my fuel pump sensor replaced. The place told me that now the ' forgot what the name is' will need to be replaced in a few months- that once the fuel injector pump goes, the fuel injector automatically goes soon. Dodge 1998 diesel dually. 130,000 miles. Is this a norm? I think it is the fuel injector... I know it is expensive. How easy/hard is it to replace? My son in law is good with repairing cars- I don't know if this is something he can do- he is an engineer (I don't know 'what kind'). Thanks.