1st person space ship pitch and yaw isue - unity3d

Question

I've been trying for some time now with different tutorials to get a nice firstperson (cockpit view) spaceship controll system. I tried using mouse only, keyboard only and combinations but I keep encountering the same problem with all tutorials. even this simple line of code does it:
transform.position += transform.forward * Time.deltaTime * 90f;
transform.Rotate( Input.GetAxis("Vertical"), Input.GetAxis("Horizontal"), 0.0f);
The problem I keep getting is that if I pitch its ok. it I yaw its ok. But If I do both (so I go diagonaly) it also rotates my ship on the Z axis and messes up my orientation. I tried locking the z rotation in the rigidbody but that does'nt help either. I tried making code myself alternating with apply torque and simply rotating, followed some tutorials including this one: Tutorial but keep getting the rotation problem.
What I want to make is a game that controlls like the old game Helbender
Does anyone of you know of a way that I can get spaceship controlls to work?
----EDIT-----
Got a bit further now. It doenst turn on my z axis anymore becouse I keep setting it to 0. Only problem now is that if I try to make a looping the ship flips around instead of nicely looping.
if (Input.GetKey("up"))
{
transform.Rotate(transform.right * -ShipPanSpeed * Time.deltaTime, Space.World);
}
if (Input.GetKey("down"))
{
transform.Rotate(transform.right * ShipPanSpeed * Time.deltaTime, Space.World);
}
if (Input.GetKey("left"))
{
transform.Rotate(transform.up * -ShipPanSpeed * Time.deltaTime,Space.World);
}
if (Input.GetKey("right"))
{
transform.Rotate(transform.up * ShipPanSpeed * Time.deltaTime,Space.World);
}
float z = transform.eulerAngles.z;
transform.Rotate(0, 0, -z);

Answer 1

You could always try to make one parent object for the Controls and then a child object (the spaceshit) that you can rotate for the pivot but not attach any movement beside rotation.
What i mean is that you can rotate the parent on the Y axis to make it rotate and move the transform forward or backward at the same time. If you want to pivot up or down you can transform forward at the sametime you transform up/down multiplied with the axis you want to pivot with
Example:
private void Update(){
//PARENT--------------------------------------------
// MOVING FORWARD AND BACKWARD
transform.position += transform.forward * Input.GetAxis("Vertical") * speed * Time.deltaTime();
// MOVING RIGHT AND LEFT
transform.position += transform.right * Input.GetAxis("Horizontal") * speed * Time.deltaTime();
//PIVOT UP AND DOWN
transform.position += transform.up * -Input.GetAxis("Mouse Y") * speed * Time.deltaTime();
//ROTATE AROUND THE Y AXIS
tranform.Rotate(0f, Input.GetAxis("Horizontal") * rotationspeed, 0f);
}
For the spaceship (child) for the pivot i would recommend you to make a emptyobject and set the chip to lookAt that object based on the input axis you use to move up/down and forward/backward.
Hope this helped or at least gave you a idea of how to make it :)