humming noise & not starting after its been running awhile

thanks .... i went to one place for them to put it on the machine and the guy told me it "might" be the EGR valve but he didn't sound real sure of himself. I was hoping that there was something I could check myself before I started letting someone start charging me for random things. Maybe I could go to another mechanic shop that is more reputable. Thanks again!

Yes, it could be the EGR valve, but you will waste your money unless know it for sure. I'd suggest a good diagnostic from a good shop. Did the shop gave you the exact DTC? It should be a letter P and 4 numbers after. The code won't "tell you" what's the problem is, just indicates where to look for. Dirty or failing EGR valve could stuck open and causing problem with the intake manifold pressure and unmeasured air flow, so it could be the problem, but you really want to be sure. Zee