Is a 1999 Pontiac Grand Am 4 cylinder engine interchangable with 1995 cylinder?

No, a 1999 Pontiac Grand Am 4-cylinder engine is generally not interchangeable with a 1995 Pontiac Grand Am 4-cylinder engine without significant modifications, if at all. While both may be 4-cylinder engines, there were changes in engine design, computer systems, and related components over those four years. Even if the engine displacement is the same, the specifics (like sensors, mounting points, wiring harnesses, etc.) will likely differ substantially. You'd be facing a major undertaking to make such a swap work.