1987 350 5.7liter chevy - engine
 

Been having a trouble light pop on once in a while.
Problem is...as soon as it lights up, it's as if the engine lost 2 cylinders...runs rougher, noticeable powerloss.
If I pull over and turn off the key, I can start it back up right away and it's back to normal.

Does this sound familiar to anyone?

....just had a new computer installed last year.

RE: 1987 350 5.7liter chevy - engine
 

Electrical or spark related, maybe?
Check rotor, wires, plugs, distributor, coil, ignition timing, etc.
My $.02...