1999 Plymouth Voyager running rough and stalling

My 1999 plymouth grand voyager has two problems. First at times in the cold weather it will run rough when I star it up. Not all the time though. I will have to have it up to 2,000 rpm for a couple of minutes to run right. Second it will die when it is warm when slowing down at times the rpm will go 1000 to 500 to 1000 & 500 and die. This stalling is smooth on the speeding up and down of the engine. I have cleaned all grounds and added a new groung from the motor mount to frame. The plugs are ok. The computer and coils and module have been changed in the past from chrysler said the previous owner. I had this hooked up in cold weather in a computer and found nothing. It ran fine that day. There is no codes but had 29 previous codes that were erased. The idle air moves up when the computer tells it to. The map sensor seemed ok too. It was around 2 degress F and the temp sensor said 7 0r 8 volts. What would this reading be in F? Do you have any ideas before I change stuff out? Every time the engine stallls it starts right up. The fuel pressure checks out ok too.

Thanks

Larry