humming noise & not starting after its been running awhile on 2000 Saturn LS2

my car cranks great in the mornings, but I have noticed that after I have used it for awhile if I turn it off it seems to take around 30 minutes to restart. It makes a humming noise as well going down the road. Could it be my fuel pump or maybe some kind of sensor going out? My service engine soon comes on then goes back off constantly! I had my battery tested .... it's fine. The engine tries to turn over, but just seems to not be getting the connection after it's been in use for awhile! HELP!

Asked by for the 2000 Saturn LS2
It could be quite few thing. I'd definitely get a computer diagnostic, it will shine some light on what's really going on. Even if the Check Engine Light off, they will be able to pull trouble code(s) out from the ECM's memory.

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.