I recently purchased my GTP and fell in love with it, however the car got to a point where it would hardly drag itself into the drive (no exaggertain) I took it to a local shop and they did a complete tune up of the car. The thing ran great after that. Recently I noticed that the car with cut out when going up a hill but then be just fine when either A.) I gave it more gas or B.) it was done going up the hill.

Well the other day I go into that gas station and left the car running, when I came back out the car was barely running and it was spitting and sputtering then it died. It would start back up then die again, it took 20min to home when I live just 3 blocks away. I have gone back out to start it and it fires right up but when I go to give it gas it cuts out again, doesnt die just cuts out. What could be wrong with this thing????