# opening file 1
# ...
my %hash;
while (my $line1=<TR>)
{
    chomp($line1);
    my @ar = split(/\t/,$line1);
    $hash{$ar[1]} = $ar[3];
}
close TR;

open my $SC, "<", $file2 or die "Error blah blah... $!";
while (my $line2 = <$SC>) 
{
    my ($id, $val) = split /\t/, $line2;
    my $val_file1 = $hash{$id};
    if ( $val > $val_file1 - $margin and $val < $val_file1 + $margin) {
        # print out something
    }
}
close $SC;