My 1997 tj 4.0 has seem to be getting slower to start over the months. I have started to have to prime it with 2-4 steps of gas to get it to start quicker. Last couple of days it has done it but seem like it would slow on the third turn and seem like it isn't about to start then it shakes and aggressively turns on. It didn't turn on once and right before i was about to try and get jumped i tried again with some more gas and it worked. Any suggestions? battery? starter?