Present tenses for the future with GOING TO DO … I’m going to do something …
I’m going to do it. you’ve decided to do something.
Ex: I’m going to the cinema tonight, do you want to come?
Differences I’m doing something / I’m going to do something ?
I’m doing it: you want to do it, and you’ve arrange it!
I’m leaving tomorrow on holidays. (I’ve booked tickets, hotel, etc…)
≠
I’m going to do it: you want to do it, you intend to do it, but you haven’t arranged it!
I’m going to NYC next summer (but I haven’t booked tickets!)
With was/were going to do it:
I was going to do something …
I was going to take the plane, but I missed it!
Here, the meaning is:
you wanted to do it, you intented to do it, but: you didn’t do it !!
FUTURE: