I am going to..

I'm going to + verb should not be translated literally (in some cases). In French you would say: je vais + verb, in Italian such expression doesn't exist, unless of course what you mean to say is I am going from A to B, as in:

I’m going to Rome
Vado a Roma

Are you going to work today?
Vai a lavorare oggi?

I’m going to phone the police (if you are literally going from A to B in order to make the phone call)
Vado a telefonare alla polizia

If what you mean to do is signal a personal intention or make a prediction, do not use the verb “to go”. You should use instead the present tense, occasionally the future, or possibly the construction stare per + verb:

Today I’m going to throw away all my old clothes
Oggi butto tutti i miei vecchi vestiti
or
Oggi ho intenzione di buttare tutti i miei vecchi vestiti

When I grow up I’m going to be a pilot
Da grande farò il pilota

It is going to rain
Sta per piovere

I’m going to faint
Sto per svenire