97 Plymouth voyages 3.3 starts great but dies when I put it in R or D. Put in neutral or park starts again. What is wrong?

Could be a number of thing's , ignition system related , engine sensor's . The only way to know for sure would be to do some testing . I have seen crankshaft position sensors , cam sensors , coolant temp . sensors , mass air flow sensors, . It's just not that simple , what is wrong . U don't want to replace a bunch of parts that won't fix the problem . Your best bet would be to have it diagnosed at a qualified repair shop . It takes specialized tools to track down problems like this .