5xx response code error Irule issue

I think you should try to make this a bit clearer.

I've rewritten your original rule in a nicer formatting in case someone else understood the initial description:

when CLIENT_ACCEPTED { 
    set count 0 
}

when HTTP_REQUEST priority 800 { 
    set request [HTTP::request]
}

when LB_SELECTED { 
    if { $count >= 1 } { 
        log local0. "Deleting cookie 73686f706c656e6f766f with value \"[HTTP::cookie value 73686f706c656e6f766f]\"" 
        HTTP::cookie remove "73686f706c656e6f766f" 
        LB::reselect pool pool-test_shop.kpr.com_http 
        log local0. "Reselection: member [LB::server addr]:[LB::server port] from pool [LB::server pool]" 
    } 
}

when HTTP_RESPONSE priority 800 { 
    if { [HTTP::status] eq 503 && $count < 3 && [LB::server pool] == "pool-test_shop.kpr.com_http"} { 
        incr count
        HTTP::retry $request 
        log local0. "[HTTP::status] from [LB::server addr]:[LB::server port], trying another [LB::server pool] member (retry $count)" 
    } elseif { [HTTP::status] == 503 && $count >= 3 } { 
        HTTP::redirect "http://www.kpr.com" 
        set count 0 
        log local0. "Redirect to dotcom due to panic mode (retried pool [LB::server pool] $count times)" 
    } elseif { ! ( [HTTP::status] eq 503 ) && $count >= 1 && [LB::server pool] == "pool-test_shop.kpr.com_http" } { 
        set count 0 
    } elseif { $count >= 1 && ! ( [LB::server pool] == "pool-test_shop.kpr.com_http" ) } { 
        log local0. "Retry count = $count for pool [LB::server pool] -- this connection is being reused" 
    }
}

/Patrik