i tried using the action trigger event but it only trigger for the first frame only then never detect it again
Have you checked in the "every frame" toggle?
but still the bigger problem the controller max forward speed variable , how to set it in run time ?
Well, I won't pretend I have spent much time with the Unity's default character controller (which's what I assume you're using), so I might be quite off in what I'll say here. I have many reasons to prefer using a standard rigidbody/collider and build my own controller on top of it - one of them being that I get full control of how things happen. Max speed is one of those things, in the default character controller you set that parameter directly in one of the character controller components (IIRC, there are two). Now, if you want to make that change-able straight from Playmaker - what you want, if I understood correctly - you'd need a specific action to do it.
There's no built-in/easy way right now for Playmaker to "see" some component attribute, you can turn it on or off and you can code your component (script) to send and receive parameters from a Playmaker FSM but that's it. Personally I prefer to have everything in action format instead of mixing standard scripts with actions, except if the script does something standalone that doesn't need communication with any other systems, like a game-start object instancer for example. Alex did mention some plans to make these component parameters easier to access/change btw.
That said, considering that what you're asking for is pretty trivial, you should probably post an 'action request' for that in the appropriate forum. Who knows, I might even code that in myself once I get some free time
Good luck!