First off, I would never try to start an LT5 of unknown history (especially one that apparently has not been started in two years if that is what you mean by "sitting outside") without first checking/replacing all fluids. Then a compression check, Then some more checks on plugs, injectors and vacuum system pump cycling. A Fuel rail/system that has dried out because of non use may have additional issues.
LT5/ZR-1 Fluids
White smoke indicates moisture. I would stutter also after sitting outside for two years
Also.....how many miles on the 1990?
Run a Check Engine Code Check......you might find all sorts of Codes after sitting outside for two years including O2 sensors, INFL REST, and several others.
Welcome to the Forum 
Lots of guys here will be talking your ear off after we get a bit more feed back from you on the Codes, and if in fact this LT5 has not been run in two years
