2005 GMC ENVOY User Comment / Complaint

My 2005 gmc envoy continues to have the same problem over and over. i'm taking it in again today for the 4th time. it loses power going up hills. it's like the engine is stalling, and it has actually cut off on me. the first 2 times they could find nothing wrong. so it didn't get fixed. the 3rd time the check engine light finally came on. they said it was the oxygen sensor, and carbon build up on the fuel solenoid. once again the check engine light is on. this time i had onstar do a diagnostic test. i was informed that there is a power train system malfunction. which is the part of the engine system that provides power to move the vehicle. obviously this has been the problem all along that the dealership can not seem to fix. of course the gas mileage is terrible due to this situation, and with gas prices the way they are it's killing me.