I have a 97 grand cherokee tsi (with 239K miles). It is turning over for a long time before actually starting (it does still start every time, but it is getting worse and worse). It then shutters and makes some noises for a few seconds after finally starting. If I turn it off just for a small amount of time (less than a half hour) and then start it back up it doesn't have this problem, usually starts right up. Anyone have any idea what the problem is? Fuel pump?