2005 sonata won't start
 

my 2005 sonata has a peculiar problem. it won't start after running for a while(say for an hour) but not every time,once in week sometimes once in a month. it cranks but will not start it starts when i remove battery connections for a minute or 2 and reconnect . can anyone there help me.
hyundai mechanics (here in india) tried all they knew still couldn't slove the problem.
it also jerks/misfires at lower speeds