What is wrong with my van?

1999 Plymouth Voyager. The van hesitates, then runs good, but it takes a while for it to shift into gear, the brakes are grinding. In the morning when I first start the van up it takes a while for it to go into reverse, it rolls forward then shifts into reverse realy hard. The oil light falshes on and off when I come to a stop(there is oil in the van). After a stop when you go the van hesitates(like bucking)I ease up on the gas and then it picks up. Help!