my jeep always takes a couple strokes of the key to get started, if you crank for a couple seconds then stop it will always fire right up on the second try. Now after it starts it will stumble and sound like its only running on 5 cylinders. It will do this for 5 to 10 seconds then smooth out and run like normal. I'm sure I have to replace my fuel pump as if you cycle the key a few times to prime it, it will start like a champ. My question is what would be causing it to stumble?

 

It could be the regulator on the top of the pump, but if you're going to drop the tank to replace that, you might as well do the whole pump.