My car has has 40 miles put on it in 3 years and I finally got it registered. I put in a new fuel filter, thermostat housing, and thermostat, oil change. Yesterday I got it out and put about 50 miles on it with no problems. Today I took it out and put another 20 miles on and for some reason it started to put and jerk hard. I pulled over thinking it was possibly a fuel pump. Gave the gas tank a couple hits and then shook the car a little bit. Drove it away no problems. Got it home and it cooled. Took off again. It started fine then it did it again once I drove it for a minute. This time I just sat there for a minute and it fired right up and then it drove fine. Then I let it cool and I took it out again. Once it warmed up it did it again. This time I left it running and it fixed itself. What could be the problem?