red 59

I put my truck in the dealer on tuesday because it would die when it gets hot. I got it back today and they first the egr system was bad then they "discovered " the check engine light was burt out. They put in a new one and they said they reset the o2 sensor codes and the A/F meter. The truck has not died yet this evening but it is still shaking . I would like to check the egr system but Im not sure how to.