start problems

1994 pontiac grand am,got to work put car in reverse car stalled ,started car in drive car was o.k. left work at end of day, was driving and speedometer would go haywire when put on brakes and almost stall, finally after about half hour driving car did stall out and did't restart. two hours later went back started car made it home,turn off car and tried to start ok until I put in reverse now won't start at all thanks for any help