Google turned up nothing on shelf life. Banned in 1997.
I still have a couple gallons, 25-30 years old stored in a metal gas can.
I know it's toxic, haven't used it in years. Is it safe to keep or should I
turn it for disposal? Best degreaser I ever used.

I'd get rid of it. From my recollection, it was usually doped with under 10% added stabilizers to keep it from degrading and becoming acidic, which could be an issue in a metal container.

It can break down to make some nasty stuff like phosgene and eventually hydrochloric acid.

While a pristine lot of the stuff, stored well sealed in an appropriate container, may still be good, are you willing to bet on your stuff?

Thanks. I would like to keep my old gas can.
would it be safe to put in plastic jugs to take for disposal?

Depends on the plastic. Teflon is ok, HDPE and PP may be ok temporarily. Do a spot check to see if there is any immediate reaction (like dissolution!)