1999 Chrysler Intrepid Hesitates on Cold Start

About two months ago, my 1999 Chrysler Intrepid started showing a slight hesitation on cold startup. Once it starts it runs fine and without any performance problems whatsoever. After the car has been running for the day it starts up fine. It's only when the car has been sitting cold overnight. It's still very warm outside so it's not a temperature issue but I'm worried that the coming winter months will make the problem worse. Last winter, I replaced the cam and crank sensors, and fuel pump to deal with a problem with stalling while driving. That's been fine since. Recently, to try and resolve the problem, I've gotten an oil change (5W30 Synthetic), replaced the oil filter, replaced the air filter, and I had them do a fuel system service to clean the injectors. The performance has been increased but I still get the hesitation on cold start. I want to do more to prepare it for winter and I'm wondering what the best choice is and what could be causing this problem on cold start. Should I replace the spark-plugs and wires? Should I get a tuneup? What's next? Any advice would be greatly appreciated. Thank you!