99 3500 stalls when coming to a stop...

Been a long time since Ive been around on the forums but here it goes. I came up an really sweet deal, 99 C3500 CC with V454 and 65K on the clock. Really clean truck inside and out. The guy I purchased from only used truck on weekends to pull his 53' goose neck enclosed race trailer. I have an extra PCM for towing and for standard driving OG unit is used. This was a deal I could not say no to. My dilemma now is that when driving in standard conditions and at all normal rates, the truck dies when coming to a stop. Fires right back up and everything is gravy. This problem is getting very annoying. Ive had the IAC changed and it still persists. Thought it could have been T-Converter lock up solenoid, no dice. Now allegedly there is a PCM issue that requires factory programming, is this an issue any of you guys have come across? Everything works on this truck with no codes once so ever. I have 67K on it now, Any help would be great..