Need help of I-rule rewrite

At a minimum there's an iRule syntax issue:

when HTTP_REQUEST {
    if { [string tolower [HTTP::host]] starts_with "lmjedwmsaphchh.jeddah.cpksa.local" } { 
        HTTP::header replace Host "lmjedwmsaphchh.jeddah.cpksa.local:7778" 
    } 
} 
when HTTP_RESPONSE {
    if { [HTTP::is_redirect] } {
        HTTP::header replace Location [string map {"lmjedwmsaphchh.jeddah.cpksa.local:7778" "lmjedwmsaphchh.jeddah.cpksa.local"} [HTTP::header Location]]
    }
}

This will account for the incoming Host header and any outgoing redirect Location headers. If it still doesn't work, I'd do a capture of the traffic on the client side to see if other :7778 references are getting through to the client (ie. document object references).