1998 Dodge Caravan Hard Starting

My Grand Caravan 3.8 liter is having difficulty starting. It went from starting almost immediately to taking three or four attempts about 5-7 seconds each to start. It seems to run fine after it is going. If I turn it off briefly and start it again, it starts better but not "normally." However, after it sits any length of time, it takes multiple tries to start. I replaced all the spark plugs when it first occurred but it didn't resolve the problem. In addition, the starter now sounds as though it is making unusual noises as well. The starter is an after market starter which I replaced two years ago.