Chrysler has followed rivals Ford and General Motors by announcing plans to cut back on the production of minivans in the US, as rising fuel prices drive consumers to opt for smaller vehicles.   Two factories in Missouri are affected, with one minivan plant in St Louis shutting down completely and another cutting back from two shifts to one. The reductions will lead to a cut of 2,400 hourly jobs.   "The market is fairly slow and consumer confidence has been down," said Chrysler president Jim Press.