Well my jeep has done this since i bought it and i'm finally going to try to figure it out. When my jeep sets for a long period of time it has a hesitation. Starts fine, but after about 30 seconds it falls on its nose, like it's not getting fuel. Back off the gas and then get back on it and it goes away. I've replaced the fuel pump, but I'm thinking its the cps or tps. Any ideas?