So do you know if this is for all mustangs or manual cars?

Put car in 1st gear and release clutch very slowly until it crawls.

The tach doesn't want to stay steady and chokes and near stalls like I am riding a mad donkey lol.

Is this normal?

 

???? Any manual car lugged like this will start bucking. Use clutch slippage to manage this not throttle. Is this your first stick car?

 

Yeah, use the gas pedal with the clutch pedal to find the sweet spot for a smoother take off. You'll need to experiment with how much gas exactly to give and with how slow to release the clutch pedal.

If you're still learning how to drive a manual transmission, take the car to an empty parking lot and try stop/starting several times until you get the hang of it.