is there any movie franchise besides terminator that has movies set in different decades? like the first was made in 80s, t2 was released in 1991, t3 in 2003.

You seem to be asking two different things; movies set in different decades, vs movies released in different decades. Which is it?

So each part of the trilogy released in a separate decade?

The first three Alien films came out in different decades, and Alien took place in a different decade than Aliens and Alien3, and Resurrection took place in a different century than the others.

I win.

The Black Stallion?.... http://en.wikipedia.org/wiki/List_of_movie_trilogies

Franchises, or trilogies?
Made in, or set in the decade?

If you are talking about franchise movies made over different decades:
James Bond - five
Rocky - four
Star Wars - four

the up series

it's franchises/trilogies made in separate decades.

Even though they expand on trilogies:

Antoine Doniel
Romero's "Dead" series
Zatoichi
Wong Fei Hung series (Starring Kwan Tak Hing)

The British "Carry On" movies

http://en.wikipedia.org/wiki/Carry_On_films

Predator - 1987
Predator 2 - 1990
Alien vs. Predator - 2004

Do you mean all the movies in the series in different decades or just 2 out of the 3?

The Godfather series and Jurassic Park were in 2 different decades but not 3.

The Friday the 13th series could be considered in 3 decades if you count Freddy vs Jason as part of the Friday series.

Oh,

Gremlins 1984
Gremlins 2 1990