Van Starts up fine 1st time, Then Misfires

My grandfather has a 94 Voyager with the v6 in it. He just got it and the previous owner didn't tell us much about it. Now whenever you start the van for the first time of the day, it runs fine, but if you shut it off and start it again within several hours, the number one cylinder misses. The obvious things have been changed, plugs,wires,dist cap, and I even think they changed the computer. I don't want my grandfather to spend a fortune having the mechanics try to figure out what's wrong so could you guys give me your $.02? It's already been at the shop waaay to long. Thanks in advance.

I would have a compression test first, if the compression is OK then I would have the injectors inspected and cleaned.
You did not mention which v6 he has, that can make a lot of difference regarding the answers people are going to give you.