Warm starting is a mess

Heya! My golf ran perfectly!

*Ran*

The newest addition to the ever growing list! : It doesnt want to start when warm.

I have replaced : fuel tank sender, rubber fuel lines, pressure regulator, fuel pump, had all hardlines pressure tested, fuel filter and the entire injection system was professionally rebuilt.

With everything brand new it ran as it should, until about a week ago. Cold start is no problem, but as soon as i go into the Shops and come back after more than 10 seconds im cranking for a solid 10 minute before it sputters to life.

If the engine is warm and i turn it off, and immediatly turn it on again. It runs like it should. But anything longer than about 10 seconds and im cranking away.

If i wait a 15 minutes between turning off the engine and restarting, it immediatly shoots to life but to die as fast as it started.

The only thing i can think of would be an injector thats "dieseling" and keeps dripping so the mixture cant ignite.

I would very very much appriciate more opinions on what could be causing it.

(P.s. engine has a tendency to run at 800-850 rpm when i come to a stop, havent figured that one out yet either.

Many many thanks!