well.. I also know that no body wants to write a code for free.. I have asked for the help not for the entire code..

#!/usr/bin/perl
use strict;
open (FILE, "ip.txt") || die "can't: $!";
open (OUTPUT,">op.txt") || die "can't: $!";
my @lines=();
my @l1=();
my @l2=();
@lines=<FILE>;
my %hash=();
my $i=0;
my $j=$i+1;
my @arr1=();
my @arr2=();
my @arr3=();
while($j <= $#lines)
{
    #print "$j\n";
    @l1=split(/\t/,"$lines[$i]");
    @l2=split(/\t/,"$lines[$j]");
    if(abs($l2[3]-$l1[3]) <= 500 && $l1[6] eq $l2[6])
    {
        $hash{$lines[$j]}=1;
        if(!exists $hash{$lines[$i]})
        {
            $hash{$lines[$i]}=1;
            push(@arr1,$l1[3]);
            push(@arr2,$l1[7]);
            push(@arr3,$lines[$i]);
            #print OUTPUT "$lines[$i]";
        }
        #print OUTPUT "$lines[$j]";
        
        push(@arr1,$l2[3]);
        push(@arr2,$l2[7]);
        push(@arr3,$lines[$j])
    }
    else
    {
        @s_arr2=sort{$a<=>$b}@arr2;
        if($s_arr2[-1]-$s_arr2[0] <= 500)
        {
//got struck
    $i=$j;
    $j=$i+1;

}
[download]

Thanks.